diff --git a/internal/lsp/cmd/test/cmdtest.go b/internal/lsp/cmd/test/cmdtest.go
index d31dfe4..c04bb91 100644
--- a/internal/lsp/cmd/test/cmdtest.go
+++ b/internal/lsp/cmd/test/cmdtest.go
@@ -53,6 +53,10 @@
 	//TODO: add command line completions tests when it works
 }
 
+func (r *runner) CaseSensitiveCompletions(t *testing.T, data tests.CaseSensitiveCompletions, items tests.CompletionItems) {
+	//TODO: add command line completions tests when it works
+}
+
 func (r *runner) RankCompletions(t *testing.T, data tests.RankCompletions, items tests.CompletionItems) {
 	//TODO: add command line completions tests when it works
 }
diff --git a/internal/lsp/completion_test.go b/internal/lsp/completion_test.go
index be42932..d786218 100644
--- a/internal/lsp/completion_test.go
+++ b/internal/lsp/completion_test.go
@@ -98,6 +98,21 @@
 	}
 }
 
+func (r *runner) CaseSensitiveCompletions(t *testing.T, data tests.CaseSensitiveCompletions, items tests.CompletionItems) {
+	for src, test := range data {
+		got := r.callCompletion(t, src, source.CompletionOptions{
+			CaseSensitive: true,
+		})
+		if !strings.Contains(string(src.URI()), "builtins") {
+			got = tests.FilterBuiltins(got)
+		}
+		want := expected(t, test, items)
+		if msg := tests.DiffCompletionItems(want, got); msg != "" {
+			t.Errorf("%s: %s", src, msg)
+		}
+	}
+}
+
 func (r *runner) RankCompletions(t *testing.T, data tests.RankCompletions, items tests.CompletionItems) {
 	for src, test := range data {
 		got := r.callCompletion(t, src, source.CompletionOptions{
diff --git a/internal/lsp/source/completion.go b/internal/lsp/source/completion.go
index 8fa06c3..12d036e 100644
--- a/internal/lsp/source/completion.go
+++ b/internal/lsp/source/completion.go
@@ -104,11 +104,21 @@
 	Score(candidateLabel string) (score float32)
 }
 
-// prefixMatcher implements case insensitive prefix matching.
+// prefixMatcher implements case sensitive prefix matching.
 type prefixMatcher string
 
 func (pm prefixMatcher) Score(candidateLabel string) float32 {
-	if strings.HasPrefix(strings.ToLower(candidateLabel), string(pm)) {
+	if strings.HasPrefix(candidateLabel, string(pm)) {
+		return 1
+	}
+	return -1
+}
+
+// insensitivePrefixMatcher implements case insensitive prefix matching.
+type insensitivePrefixMatcher string
+
+func (ipm insensitivePrefixMatcher) Score(candidateLabel string) float32 {
+	if strings.HasPrefix(strings.ToLower(candidateLabel), string(ipm)) {
 		return 1
 	}
 	return -1
@@ -233,8 +243,10 @@
 
 	if c.opts.FuzzyMatching {
 		c.matcher = fuzzy.NewMatcher(c.surrounding.Prefix(), fuzzy.Symbol)
+	} else if c.opts.CaseSensitive {
+		c.matcher = prefixMatcher(c.surrounding.Prefix())
 	} else {
-		c.matcher = prefixMatcher(strings.ToLower(c.surrounding.Prefix()))
+		c.matcher = insensitivePrefixMatcher(strings.ToLower(c.surrounding.Prefix()))
 	}
 }
 
diff --git a/internal/lsp/source/options.go b/internal/lsp/source/options.go
index 7d35fa6..d3c95cd 100644
--- a/internal/lsp/source/options.go
+++ b/internal/lsp/source/options.go
@@ -76,6 +76,7 @@
 type CompletionOptions struct {
 	Deep              bool
 	FuzzyMatching     bool
+	CaseSensitive     bool
 	Unimported        bool
 	Documentation     bool
 	FullDocumentation bool
@@ -200,6 +201,8 @@
 		result.setBool(&o.Completion.Deep)
 	case "fuzzyMatching":
 		result.setBool(&o.Completion.FuzzyMatching)
+	case "caseSensitiveCompletion":
+		result.setBool(&o.Completion.CaseSensitive)
 	case "completeUnimported":
 		result.setBool(&o.Completion.Unimported)
 
diff --git a/internal/lsp/source/source_test.go b/internal/lsp/source/source_test.go
index a91a28f..d4058e9 100644
--- a/internal/lsp/source/source_test.go
+++ b/internal/lsp/source/source_test.go
@@ -210,6 +210,24 @@
 	}
 }
 
+func (r *runner) CaseSensitiveCompletions(t *testing.T, data tests.CaseSensitiveCompletions, items tests.CompletionItems) {
+	for src, test := range data {
+		var want []protocol.CompletionItem
+		for _, pos := range test.CompletionItems {
+			want = append(want, tests.ToProtocolCompletionItem(*items[pos]))
+		}
+		_, list := r.callCompletion(t, src, source.CompletionOptions{
+			CaseSensitive: true,
+		})
+		if !strings.Contains(string(src.URI()), "builtins") {
+			list = tests.FilterBuiltins(list)
+		}
+		if diff := tests.DiffCompletionItems(want, list); diff != "" {
+			t.Errorf("%s: %s", src, diff)
+		}
+	}
+}
+
 func (r *runner) RankCompletions(t *testing.T, data tests.RankCompletions, items tests.CompletionItems) {
 	for src, test := range data {
 		var want []protocol.CompletionItem
diff --git a/internal/lsp/testdata/casesensitive/casesensitive.go b/internal/lsp/testdata/casesensitive/casesensitive.go
new file mode 100644
index 0000000..6f49d36
--- /dev/null
+++ b/internal/lsp/testdata/casesensitive/casesensitive.go
@@ -0,0 +1,16 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package casesensitive
+
+func _() {
+	var lower int //@item(lower, "lower", "int", "var")
+	var Upper int //@item(upper, "Upper", "int", "var")
+
+	l //@casesensitive(" //", lower)
+	U //@casesensitive(" //", upper)
+
+	L //@casesensitive(" //")
+	u //@casesensitive(" //")
+}
diff --git a/internal/lsp/tests/tests.go b/internal/lsp/tests/tests.go
index 6e647ab..aa08245 100644
--- a/internal/lsp/tests/tests.go
+++ b/internal/lsp/tests/tests.go
@@ -29,26 +29,27 @@
 // We hardcode the expected number of test cases to ensure that all tests
 // are being executed. If a test is added, this number must be changed.
 const (
-	ExpectedCompletionsCount           = 169
-	ExpectedCompletionSnippetCount     = 36
-	ExpectedUnimportedCompletionsCount = 1
-	ExpectedDeepCompletionsCount       = 5
-	ExpectedFuzzyCompletionsCount      = 6
-	ExpectedRankedCompletionsCount     = 1
-	ExpectedDiagnosticsCount           = 21
-	ExpectedFormatCount                = 6
-	ExpectedImportCount                = 2
-	ExpectedSuggestedFixCount          = 1
-	ExpectedDefinitionsCount           = 39
-	ExpectedTypeDefinitionsCount       = 2
-	ExpectedFoldingRangesCount         = 2
-	ExpectedHighlightsCount            = 2
-	ExpectedReferencesCount            = 6
-	ExpectedRenamesCount               = 20
-	ExpectedPrepareRenamesCount        = 8
-	ExpectedSymbolsCount               = 1
-	ExpectedSignaturesCount            = 21
-	ExpectedLinksCount                 = 4
+	ExpectedCompletionsCount              = 169
+	ExpectedCompletionSnippetCount        = 36
+	ExpectedUnimportedCompletionsCount    = 1
+	ExpectedDeepCompletionsCount          = 5
+	ExpectedFuzzyCompletionsCount         = 6
+	ExpectedCaseSensitiveCompletionsCount = 4
+	ExpectedRankedCompletionsCount        = 1
+	ExpectedDiagnosticsCount              = 21
+	ExpectedFormatCount                   = 6
+	ExpectedImportCount                   = 2
+	ExpectedSuggestedFixCount             = 1
+	ExpectedDefinitionsCount              = 39
+	ExpectedTypeDefinitionsCount          = 2
+	ExpectedFoldingRangesCount            = 2
+	ExpectedHighlightsCount               = 2
+	ExpectedReferencesCount               = 6
+	ExpectedRenamesCount                  = 20
+	ExpectedPrepareRenamesCount           = 8
+	ExpectedSymbolsCount                  = 1
+	ExpectedSignaturesCount               = 21
+	ExpectedLinksCount                    = 4
 )
 
 const (
@@ -67,6 +68,7 @@
 type UnimportedCompletions map[span.Span]Completion
 type DeepCompletions map[span.Span]Completion
 type FuzzyCompletions map[span.Span]Completion
+type CaseSensitiveCompletions map[span.Span]Completion
 type RankCompletions map[span.Span]Completion
 type FoldingRanges []span.Span
 type Formats []span.Span
@@ -83,29 +85,30 @@
 type Links map[span.URI][]Link
 
 type Data struct {
-	Config                packages.Config
-	Exported              *packagestest.Exported
-	Diagnostics           Diagnostics
-	CompletionItems       CompletionItems
-	Completions           Completions
-	CompletionSnippets    CompletionSnippets
-	UnimportedCompletions UnimportedCompletions
-	DeepCompletions       DeepCompletions
-	FuzzyCompletions      FuzzyCompletions
-	RankCompletions       RankCompletions
-	FoldingRanges         FoldingRanges
-	Formats               Formats
-	Imports               Imports
-	SuggestedFixes        SuggestedFixes
-	Definitions           Definitions
-	Highlights            Highlights
-	References            References
-	Renames               Renames
-	PrepareRenames        PrepareRenames
-	Symbols               Symbols
-	symbolsChildren       SymbolsChildren
-	Signatures            Signatures
-	Links                 Links
+	Config                   packages.Config
+	Exported                 *packagestest.Exported
+	Diagnostics              Diagnostics
+	CompletionItems          CompletionItems
+	Completions              Completions
+	CompletionSnippets       CompletionSnippets
+	UnimportedCompletions    UnimportedCompletions
+	DeepCompletions          DeepCompletions
+	FuzzyCompletions         FuzzyCompletions
+	CaseSensitiveCompletions CaseSensitiveCompletions
+	RankCompletions          RankCompletions
+	FoldingRanges            FoldingRanges
+	Formats                  Formats
+	Imports                  Imports
+	SuggestedFixes           SuggestedFixes
+	Definitions              Definitions
+	Highlights               Highlights
+	References               References
+	Renames                  Renames
+	PrepareRenames           PrepareRenames
+	Symbols                  Symbols
+	symbolsChildren          SymbolsChildren
+	Signatures               Signatures
+	Links                    Links
 
 	t         testing.TB
 	fragments map[string]string
@@ -123,6 +126,7 @@
 	UnimportedCompletions(*testing.T, UnimportedCompletions, CompletionItems)
 	DeepCompletions(*testing.T, DeepCompletions, CompletionItems)
 	FuzzyCompletions(*testing.T, FuzzyCompletions, CompletionItems)
+	CaseSensitiveCompletions(*testing.T, CaseSensitiveCompletions, CompletionItems)
 	RankCompletions(*testing.T, RankCompletions, CompletionItems)
 	FoldingRange(*testing.T, FoldingRanges)
 	Format(*testing.T, Formats)
@@ -160,6 +164,9 @@
 	// Fuzzy tests deep completion and fuzzy matching.
 	CompletionFuzzy
 
+	// CaseSensitive tests case sensitive completion
+	CompletionCaseSensitve
+
 	// CompletionRank candidates in test must be valid and in the right relative order.
 	CompletionRank
 )
@@ -209,23 +216,24 @@
 	t.Helper()
 
 	data := &Data{
-		Diagnostics:           make(Diagnostics),
-		CompletionItems:       make(CompletionItems),
-		Completions:           make(Completions),
-		CompletionSnippets:    make(CompletionSnippets),
-		UnimportedCompletions: make(UnimportedCompletions),
-		DeepCompletions:       make(DeepCompletions),
-		FuzzyCompletions:      make(FuzzyCompletions),
-		RankCompletions:       make(RankCompletions),
-		Definitions:           make(Definitions),
-		Highlights:            make(Highlights),
-		References:            make(References),
-		Renames:               make(Renames),
-		PrepareRenames:        make(PrepareRenames),
-		Symbols:               make(Symbols),
-		symbolsChildren:       make(SymbolsChildren),
-		Signatures:            make(Signatures),
-		Links:                 make(Links),
+		Diagnostics:              make(Diagnostics),
+		CompletionItems:          make(CompletionItems),
+		Completions:              make(Completions),
+		CompletionSnippets:       make(CompletionSnippets),
+		UnimportedCompletions:    make(UnimportedCompletions),
+		DeepCompletions:          make(DeepCompletions),
+		FuzzyCompletions:         make(FuzzyCompletions),
+		RankCompletions:          make(RankCompletions),
+		CaseSensitiveCompletions: make(CaseSensitiveCompletions),
+		Definitions:              make(Definitions),
+		Highlights:               make(Highlights),
+		References:               make(References),
+		Renames:                  make(Renames),
+		PrepareRenames:           make(PrepareRenames),
+		Symbols:                  make(Symbols),
+		symbolsChildren:          make(SymbolsChildren),
+		Signatures:               make(Signatures),
+		Links:                    make(Links),
 
 		t:         t,
 		dir:       dir,
@@ -295,28 +303,29 @@
 
 	// Collect any data that needs to be used by subsequent tests.
 	if err := data.Exported.Expect(map[string]interface{}{
-		"diag":         data.collectDiagnostics,
-		"item":         data.collectCompletionItems,
-		"complete":     data.collectCompletions(CompletionDefault),
-		"unimported":   data.collectCompletions(CompletionUnimported),
-		"deep":         data.collectCompletions(CompletionDeep),
-		"fuzzy":        data.collectCompletions(CompletionFuzzy),
-		"rank":         data.collectCompletions(CompletionRank),
-		"snippet":      data.collectCompletionSnippets,
-		"fold":         data.collectFoldingRanges,
-		"format":       data.collectFormats,
-		"import":       data.collectImports,
-		"godef":        data.collectDefinitions,
-		"typdef":       data.collectTypeDefinitions,
-		"hover":        data.collectHoverDefinitions,
-		"highlight":    data.collectHighlights,
-		"refs":         data.collectReferences,
-		"rename":       data.collectRenames,
-		"prepare":      data.collectPrepareRenames,
-		"symbol":       data.collectSymbols,
-		"signature":    data.collectSignatures,
-		"link":         data.collectLinks,
-		"suggestedfix": data.collectSuggestedFixes,
+		"diag":          data.collectDiagnostics,
+		"item":          data.collectCompletionItems,
+		"complete":      data.collectCompletions(CompletionDefault),
+		"unimported":    data.collectCompletions(CompletionUnimported),
+		"deep":          data.collectCompletions(CompletionDeep),
+		"fuzzy":         data.collectCompletions(CompletionFuzzy),
+		"casesensitive": data.collectCompletions(CompletionCaseSensitve),
+		"rank":          data.collectCompletions(CompletionRank),
+		"snippet":       data.collectCompletionSnippets,
+		"fold":          data.collectFoldingRanges,
+		"format":        data.collectFormats,
+		"import":        data.collectImports,
+		"godef":         data.collectDefinitions,
+		"typdef":        data.collectTypeDefinitions,
+		"hover":         data.collectHoverDefinitions,
+		"highlight":     data.collectHighlights,
+		"refs":          data.collectReferences,
+		"rename":        data.collectRenames,
+		"prepare":       data.collectPrepareRenames,
+		"symbol":        data.collectSymbols,
+		"signature":     data.collectSignatures,
+		"link":          data.collectLinks,
+		"suggestedfix":  data.collectSuggestedFixes,
 	}); err != nil {
 		t.Fatal(err)
 	}
@@ -382,6 +391,14 @@
 		tests.FuzzyCompletions(t, data.FuzzyCompletions, data.CompletionItems)
 	})
 
+	t.Run("CaseSensitiveCompletion", func(t *testing.T) {
+		t.Helper()
+		if len(data.CaseSensitiveCompletions) != ExpectedCaseSensitiveCompletionsCount {
+			t.Errorf("got %v case sensitive completions expected %v", len(data.CaseSensitiveCompletions), ExpectedCaseSensitiveCompletionsCount)
+		}
+		tests.CaseSensitiveCompletions(t, data.CaseSensitiveCompletions, data.CompletionItems)
+	})
+
 	t.Run("RankCompletions", func(t *testing.T) {
 		t.Helper()
 		if len(data.RankCompletions) != ExpectedRankedCompletionsCount {
@@ -638,6 +655,10 @@
 		return func(src span.Span, expected []token.Pos) {
 			result(data.RankCompletions, src, expected)
 		}
+	case CompletionCaseSensitve:
+		return func(src span.Span, expected []token.Pos) {
+			result(data.CaseSensitiveCompletions, src, expected)
+		}
 	default:
 		return func(src span.Span, expected []token.Pos) {
 			result(data.Completions, src, expected)