It depends on how old you are, but there's a 3 mile run involved as well as pull ups, and sit ups.
If I remember correctly, the Marine Corps does not use push ups as part of the PT assessment. They're substituted with pull ups.
EDIT** These should be the very minimum amounts to pass. If you can only do this amount, you're going to have a really hard time in boot camp..
3 pull ups (not timed)
50 crunches (2 minutes)
3 mile run (28 minutes)
These are the highest standards, for a perfect score.
20 pull ups
100 crunches
3 mile run in 18 minutes.
