If you're cat is an indoor cat, yes this product will work well for you. But if your cats go outside like mine, FORGET IT! Yes Advantage kills fleas that are on your pet immediately. But it does not keep them flea free for 30 days, like they advertise. I've tried Advantage on my cats a few times. The fleas that were on my cats did die within 12 hours. But within ONE WEEK they were biting and scratching again like before. I'm picking fleas off of them after only a week and a half. If the product wasn't so expensive, it might be worth the money. But don't waste your money, because it only works well for a few days. Frontline works a lot better.