You must have solved your problem so far but... If you haven't solved it yet, first you must tell us which version of Grub you use and then show us the entry for Mac os x in menu.lst or grub.cfg (whichever you're using). That way, it'll be easier to help you. If you're using grub legacy (that's if you have a /boot/grub/menu.lst file), the grub entry will simply be: title Mac Os X root (hd0,4) savedefault makeactive chainloader +1 This entry should direct grub to darwin, I think. grub2 is a bit complicated for me, but it should look like this: menuentry set root (hd0,5) chainloader +1 In grub2, before attempting to edit grub.cfg manually, you can test if any change will provide success by highlighting mac os x and pressing "e" as soon as you see the grub screen when you start your computer. This way, you can change the boot parameters and immediately see the results.