http://blog.mozilla.com/nnethercote/2009/05/28/mac-os-x-now-supported-on-the-valgrind-trunk/ Looks like Valgrind 3.5.0 will support the Mac! You can use it already by checking it out from the svn trunk and building it yourself. We use it in the Chromium continuous build and test system, and it has caught quite a few issues (some in Mac OS X itself, including a rather heinous ATI driver problem that crashes Display Manager). http://groups.google.com/group/vim_mac/msg/2bfd871b82c9b3b1 is an example of someone using it to find a bug in Mac Vim. (Though that was written before the merge to trunk, so it still refers to the old DARWIN branch.) Also note: if you want line numbers, you need to generate a dSYM file, which can be slow.