diff --git a/README.md b/README.md
index cf916b94..43ce1411 100644
--- a/README.md
+++ b/README.md
@@ -362,7 +362,8 @@ include the base directories (e.g., `lib/resources/file1` instead of just `file1
 Available options:
 
 + `-v`: Invert `regex_filter` (only print non-matching lines).
-+ `-l`: Print only filenames of matching files
++ `-l`: Print only filenames of matching files.
++ `-i`: Ignore case.
 
 Examples:
 
diff --git a/src/grep.js b/src/grep.js
index 3880fa19..b696792a 100644
--- a/src/grep.js
+++ b/src/grep.js
@@ -7,6 +7,7 @@ common.register('grep', _grep, {
   cmdOptions: {
     'v': 'inverse',
     'l': 'nameOnly',
+    'i': 'ignoreCase',
   },
 });
 
@@ -17,7 +18,8 @@ common.register('grep', _grep, {
 //@ Available options:
 //@
 //@ + `-v`: Invert `regex_filter` (only print non-matching lines).
-//@ + `-l`: Print only filenames of matching files
+//@ + `-l`: Print only filenames of matching files.
+//@ + `-i`: Ignore case.
 //@
 //@ Examples:
 //@
@@ -41,6 +43,9 @@ function _grep(options, regex, files) {
   }
 
   var grep = [];
+  if (options.ignoreCase) {
+    regex = new RegExp(regex, 'i');
+  }
   files.forEach(function (file) {
     if (!fs.existsSync(file) && file !== '-') {
       common.error('no such file or directory: ' + file, 2, { continue: true });
diff --git a/test/grep.js b/test/grep.js
index f450aabb..f973640c 100644
--- a/test/grep.js
+++ b/test/grep.js
@@ -137,6 +137,13 @@ test('-l option', t => {
   t.is(result.split('\n').length - 1, 2);
 });
 
+test('-i option', t => {
+  const result = shell.grep('-i', 'test', 'test/resources/grep/case1', 'test/resources/grep/case1.txt',
+    'test/resources/grep/case1.js');
+  t.falsy(shell.error());
+  t.is(result.split('\n').length - 1, 3);
+});
+
 test('the pattern looks like an option', t => {
   const result = shell.grep('--', '-v', 'test/resources/grep/file2');
   t.falsy(shell.error());
diff --git a/test/resources/grep/case1 b/test/resources/grep/case1
new file mode 100644
index 00000000..b08f7b08
--- /dev/null
+++ b/test/resources/grep/case1
@@ -0,0 +1 @@
+Test3
diff --git a/test/resources/grep/case1.js b/test/resources/grep/case1.js
new file mode 100644
index 00000000..df6b0d2b
--- /dev/null
+++ b/test/resources/grep/case1.js
@@ -0,0 +1 @@
+test3
diff --git a/test/resources/grep/case1.txt b/test/resources/grep/case1.txt
new file mode 100644
index 00000000..bac87cc8
--- /dev/null
+++ b/test/resources/grep/case1.txt
@@ -0,0 +1 @@
+TEST3