Can a monk who has natural weapon attacks (such as a centaur monk) attack unarmed and still use his natural weapons? For example, let’s say he’s a 4th-level monk. Can he use a flurry of blows and attack at +5/+5/+0 unarmed (plus other bonuses) and then at +0/+0 for 2 hooves?
If the creature normally is allowed to make both weapon attacks and natural weapon attacks as part of the same full attack routine, the monk can do the same (making unarmed strikes in place of weapon attacks). Since a centaur can make two hoof attacks in addition to his longsword attack, a centaur monk can make two hoof attacks in addition to his unarmed strike attack (or attacks, depending on his base attack bonus). The monk can’t use his natural weapon attacks as part of a flurry of blows, but he can make natural weapon attacks in addition to his flurry. Such attacks suffer the same –2 penalty as the monk’s flurry attacks in addition to the normal –5 penalty for secondary natural attacks.
An 4th-level centaur monk has a base attack bonus of +7 (+4 from his 4 monstrous humanoid Hit Dice, and +3 from his 8 monk levels). If he performs a flurry of blows, he makes three unarmed strikes, at +5/+5/+0. He can add two hoof attacks at –2/–2 (–5 as secondary weapons, and –2 from the flurry).