diff --git a/README.md b/README.md
index ff58d9a..399a27d 100644
--- a/README.md
+++ b/README.md
@@ -267,12 +267,16 @@ sed(/.*DELETE_THIS_LINE.*\n/, '', 'source.js');
 Reads an input string from `file` and performs a JavaScript `replace()` on the input
 using the given search regex and replacement string. Returns the new string after replacement.
 
-#### grep(regex_filter, file [, file ...])
-#### grep(regex_filter, file_array)
+#### grep([options ,] regex_filter, file [, file ...])
+#### grep([options ,] regex_filter, file_array)
+Available options:
+
++ `-v`: Inverse the sense of the regex and print the lines not matching the criteria.
 
 Examples:
 
 ```javascript
+grep('-v', 'GLOBAL_VARIABLE', '*.js');
 grep('GLOBAL_VARIABLE', '*.js');
 ```
 
@@ -368,3 +372,4 @@ Returns true if all the given paths exist.
 _This function is being deprecated. Use `silent(false) instead.`_
 
 Enables all output (default)
+
diff --git a/shell.js b/shell.js
index 72478c4..923be9a 100644
--- a/shell.js
+++ b/shell.js
@@ -659,18 +659,26 @@ function _sed(options, regex, replacement, file) {
 exports.sed = wrap('sed', _sed);
 
 //@
-//@ #### grep(regex_filter, file [, file ...])
-//@ #### grep(regex_filter, file_array)
+//@ #### grep([options ,] regex_filter, file [, file ...])
+//@ #### grep([options ,] regex_filter, file_array)
+//@ Available options:
+//@
+//@ + `-v`: Inverse the sense of the regex and print the lines not matching the criteria.
 //@
 //@ Examples:
 //@
 //@ ```javascript
+//@ grep('-v', 'GLOBAL_VARIABLE', '*.js');
 //@ grep('GLOBAL_VARIABLE', '*.js');
 //@ ```
 //@
 //@ Reads input string from given files and returns a string containing all lines of the 
 //@ file that match the given `regex_filter`. Wildcard `*` accepted.
 function _grep(options, regex, files) {
+  options = parseOptions(options, {
+    'v': 'inverse'
+  });
+
   if (!files)
     error('no paths given');
 
@@ -690,7 +698,8 @@ function _grep(options, regex, files) {
     var contents = fs.readFileSync(file, 'utf8'),
         lines = contents.split(/\r*\n/);
     lines.forEach(function(line) {
-      if (line.match(regex))
+      var matched = line.match(regex);
+      if ((options.inverse && !matched) || (!options.inverse && matched))
         grep += line + '\n';
     });
   });
diff --git a/test/grep.js b/test/grep.js
index e401f08..498d353 100644
--- a/test/grep.js
+++ b/test/grep.js
@@ -38,6 +38,10 @@ var result = shell.grep('line', 'resources/a.txt');
 assert.equal(shell.error(), null);
 assert.equal(result.split('\n').length - 1, 4);
 
+var result = shell.grep('-v', 'line', 'resources/a.txt');
+assert.equal(shell.error(), null);
+assert.equal(result.split('\n').length - 1, 8);
+
 var result = shell.grep('line one', 'resources/a.txt');
 assert.equal(shell.error(), null);
 assert.equal(result, 'This is line one\n');