diff --git a/HISTORY.md b/HISTORY.md
index 64185188a..ecd610c1e 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -1,8 +1,9 @@
 # History
 
 
-## not yet released, version 3.4.2
+## not yet released, version 3.5.0
 
+- Comments of expressions are are now stored in the parsed nodes. See #690.
 - Fixed function `print` not accepting an Object with formatting options as
   third parameter Thanks @ThomasBrierley.
 
diff --git a/docs/expressions/expression_trees.md b/docs/expressions/expression_trees.md
index a2efef480..ee0010918 100644
--- a/docs/expressions/expression_trees.md
+++ b/docs/expressions/expression_trees.md
@@ -201,6 +201,12 @@ All nodes have the following methods:
 
 Each `Node` has the following properties:
 
+-   `comment: string`
+
+    A string holding a comment if there was any in the expression, or else the
+    string will be empty string. A comment can be attached to the root node of
+    an expression or to each of the childs nodes of a `BlockNode`.
+
 -   `isNode: true`
 
     Is defined with value `true` on Nodes. Additionally, each type of node 
diff --git a/lib/expression/node/Node.js b/lib/expression/node/Node.js
index f23a0683d..5130e9a35 100644
--- a/lib/expression/node/Node.js
+++ b/lib/expression/node/Node.js
@@ -26,6 +26,8 @@ function factory (type, config, load, typed, math) {
 
   Node.prototype.isNode = true;
 
+  Node.prototype.comment = '';
+
   /**
    * Compile the node to javascript code
    * @return {{eval: function}} expr  Returns an object with a function 'eval',
diff --git a/lib/expression/parse.js b/lib/expression/parse.js
index 0fb4ee74f..83939231c 100644
--- a/lib/expression/parse.js
+++ b/lib/expression/parse.js
@@ -145,6 +145,7 @@ function factory (type, config, load, typed) {
 
   var extra_nodes = {};             // current extra nodes
   var expression = '';              // current expression
+  var comment = '';                 // last parsed comment
   var index = 0;                    // current index in expr
   var c = '';                       // current token character in expr
   var token = '';                   // current token
@@ -202,6 +203,7 @@ function factory (type, config, load, typed) {
   function getToken() {
     token_type = TOKENTYPE.NULL;
     token = '';
+    comment = '';
 
     // skip over whitespaces
     // space, tab, and newline when inside parameters
@@ -213,6 +215,7 @@ function factory (type, config, load, typed) {
     // skip comment
     if (c == '#') {
       while (c != '\n' && c != '') {
+        comment += c;
         next();
       }
     }
@@ -478,11 +481,14 @@ function factory (type, config, load, typed) {
 
     if (token == '') {
       // empty expression
-      return new ConstantNode('undefined', 'undefined');
+      node = new ConstantNode('undefined', 'undefined');
+      node.comment = comment;
+      return node
     }
 
     if (token != '\n' && token != ';') {
       node = parseAssignment();
+      node.comment = comment;
     }
 
     // TODO: simplify this loop
@@ -498,6 +504,7 @@ function factory (type, config, load, typed) {
       getToken();
       if (token != '\n' && token != ';' && token != '') {
         node = parseAssignment();
+        node.comment = comment;
 
         visible = (token != ';');
         blocks.push({
diff --git a/test/expression/parse.test.js b/test/expression/parse.test.js
index b8c28ff05..b70f4a453 100644
--- a/test/expression/parse.test.js
+++ b/test/expression/parse.test.js
@@ -203,6 +203,18 @@ describe('parse', function() {
       assert.deepEqual(parseAndEval('2 + 3 # - 4\n6-2'), new ResultSet([5, 4]));
     });
 
+    it('should fill in the property comment of a Node', function() {
+      assert.equal(parse('2 + 3').comment, '');
+
+      assert.equal(parse('2 + 3 # hello').comment, '# hello');
+      assert.equal(parse('   # hi').comment, '# hi');
+
+      var blockNode = parse('2 # foo\n3   # bar');
+      assert.equal(blockNode.blocks.length, 2);
+      assert.equal(blockNode.blocks[0].node.comment, '# foo');
+      assert.equal(blockNode.blocks[1].node.comment, '# bar');
+    });
+
   });
 
   describe('number', function () {