cat biting kitten

I introduced my 12 week old female to my 11 month old male last thursday with no probs. A bit of chasing around but nothing much else. Today however my male is pinning her down and biting her and she is crying out in pain. All he is doing is chasing after her to do this. This is constant. What can i do.

Is there fur flying? Is blood being drawn? Is there a significant size difference between the cats?

If the answer to these questions is "no", then you should let them sort out their relationship in cat terms. If you continuously interfere, you will only delay the process. It sounds like your male is trying to establish dominance and is telling the kitten that he is the boss. Establishing the pecking order is a neceesary aspect of a harmonious (or near-harmonious) multi-cat household.

This behavior could actually also very well be a form of play, despite what it might look and sound like.

Since males are typically larger than females, and your male cat is practically an adult while your female is still a kitten, I guess the one thing that I would be concerned about is a possible size difference. If that's in fact the case, then you may want the cats to interact only under your supervision, at least until your kitten grows more and becomes better able to handle herself.

I assume that your male has been neutered. If not, that needs to happen ASAP.