No, Thirteen has not left for good. She will be back at some point.
Cameron, on the other hand, has left for good. She left in the season 6 episode 'Teamwork'. She might come back for a guest appearance sometime in the distant future though.
Well, if you don't know that, I'm guessing you missed a few episodes? Basically, Chase lied to her about killing a patient and she laft because she felt that Chase had been corrupted by House and she didn't want to be around either of them anymore.
Oh well see I love House but ive never continuously watched the seasons. I usually just watch reruns of old episodes and stuff on like usa or something, but recently ive started really getting back into it and I was wondering what happened to Cameron. Thanks soo much for helping me out :)