Type of Action: Full-Round Action
When you withdraw, you can move up to double your speed. The square you start out in is not considered threatened by any opponent you can see, and therefore visible enemies do not get attacks of opportunity against you when you move from that square. Invisible enemies still get attacks of opportunity against you, and you can't withdraw from combat if you're blinded. You can't take a 5-foot step during the same round in which you withdraw.
If, during the process of withdrawing, you move out of a threatened square (other than the one you started in), enemies get attacks of opportunity as normal.
You may not withdraw using a form of movement for which you don't have a listed speed.
Note that despite the name of this action, you don't actually have to leave combat entirely.