D&D 3E/3.5 [3.5] Overrun - Simple Question

[Melkor]

Does the target of an overrun attack get to make his attack of opportunity before deciding whether or not just to avoid the overrun ?

 

[Norfleet]

Does the target of an overrun attack get to make his attack of opportunity before deciding whether or not just to avoid the overrun ?

Yes. He gets his attack of opportunity anyway, simply because you barged through his threatened squares, regardless of whether he avoids you or not. The actual act of performing an overrun doesn't provoke an attack of opportunity anyway, it's the act of barging through threatened squares that causes the attack of opportunity. The attack of opportunity part is listed as Step 1 of the Overrun section in the combat SRD, for exactly that reason.

Therefore, the target can take his attack of opportunity against you, regardless of whether he avoids you or not: The attack of opportunity is for barging through his square, not for the actual overrunning.