headphones not working on macbook

When I plug my headphones into my macbook, the sound just comes out of the speakers. They're plugged in all the way as far as they can go. They work on my ipod, it's just the macbook they won't work with. The sound is fine, because it's coming out of the macbook speakers...will I have to get a part replaced? Is there something I can do?

Have you tried another pair of headphones?

If it's still in warranty, just take it in and let the Apple geniuses take a look.