I am not sure in the least. My sister thinks that it has to be a girl, but I don't actually think it is. The reason I'm asking is because it's taken to overeating and then vomiting lately. So my sister thinks it must be pregnant - but I don't think pregnant cats actually behave like that. On top of which it doesn't appear to have nipples and also it's stomach is approximately the same size. I don't know - I'd much rather it were up the duff rather than preggers, but I really couldn't say. Also for the record - this ain't my cat, but it keeps coming to The House... and I keep feeding it... so it's kind of my cat. I don't even like cats. Seriously though, how do you tell a boy from a girl in terms of cats?