Why is my cat throwing up (Not hairballs?)?

Does it look like the food hasn't been chewed? My cat does the same thing because he gets excited and eats too fast. Then he gives his meal back to us, usually on the good wool rug. This happens about once every 7-10 days. Like you, we were told his blood work is normal, his teeth are healthy and his diet is good. He's been doing this for 10 years now, and he got a clean bill of health at his most recent checkup. So I guess what I'm saying is that some cats just can't hold their cat food. If your kitty was throwing up every time he ate, or even just once a day or once very other day, then it would be a cause for concern. But if this is a once a week thing and he seems otherwise completely normal, there probably isn't a problem. If he's eating and not losing weight or showing any other symptoms (patchy hair loss would indicate an allergy, for example), then it's probably nothing.