Stand up Prone

[Darkforester]

If you do a stand up action are you still under the the prone -4 to AC

[Venger]

no, you are not, because you are no longer prone.

[Mike Miller]

Standing up is a move-equivalent action that provokes an attack of opportunity. Once you are standing you are no longer prone, so no. You would not still be under the -4 penalty

[Nettlekid]

I'm going to go out on a limb and guess that you're referring to the attack of opportunity someone gets against you when you stand from prone, and the answer is that yes the attacker would benefit from you being prone for that AoO because AoOs happen before the action that provoked them resolves. So you're still prone while they attack you, and then you stand after the attack and stop being prone and stop taking the penalty.

[Venger]

I'm going to go out on a limb and guess that you're referring to the attack of opportunity someone gets against you when you stand from prone, and the answer is that yes the attacker would benefit from you being prone for that AoO because AoOs happen before the action that provoked them resolves. So you're still prone while they attack you, and then you stand after the attack and stop being prone and stop taking the penalty.

This is also why trippers can't trip you if you stand from prone in their reach, though they do get an aoo vs you.

[Rerednaw]

To the OP, if you are looking for options:

Skill tricks (Complete Scoundrel) such as Nimble Stand or Back on Your Feet help mitigate this condition by standing without provoking or as an immediate (i.e. before you are actually suffering from prone penalties).

Or you could you know, blow 1400 gp and teleport 10' away as a swift action 2/day (Anklets of Translocation, MIC)...which doesn't provoke assuming you get cover or are out of the threat area, you could then stand up.