>>Unarmed Strikes and Natural Weapons
Just as a creature can add weapon attacks to a full attack made with natural weapons, so
too can it combine unarmed attacks with natural weapons. Two options are available to accomplish this task.
A creature can choose to treat its unarmed attacks as its primary attacks and its natural weapons as secondary attacks. (This method is normally used to add weapon attacks to a natural attack routine.) The creature must make all unarmed attacks with its primary limb, which prevents that hand from being used for a natural attack such as a claw or slam. It uses its full base attack bonus for the natural attack, gaining additional attacks as normal for a high base attack bonus, and adds its full Strength bonus on damage rolls. Of course, each of these attacks provokes an attack of opportunity if the target is unarmed (unless the creature has Improved Unarmed Strike). However, its natural weapons all become secondary attacks, taking the -5 penalty on attack rolls (or -2 with the Multiattack feat) and adding only half the monster's Strength bonus on damage rolls
http://www.wizards.com/default.asp?x=dnd/rg/20070403a雖然是3R 有PF駁斥這種說法的也請拿出來