If you can afford to, all at once! It stops the bleeding immediately. By bleeding, I mean all the interest that's tacked on each month. If you can't do it all at once, definitely cut off the highest interest one first, by paying the minimum payment required on the lower interest rates and throwing the excess on the highest interest one. Once you've reached zero balance on a card, just leave it at $0. You don't need to use it and you definitely shouldn't close it because closing that account usually results in -40pt or so.