HMO's have a smaller network of people you can go to, and if you go to a non-network doctor then they pay a smaller percentage of the bill. But you typically have smaller premiums and copays with an HMO. On PPO you have more options for doctors (you can keep your existing physician in most cases), but you pay higher premiums and larger percentage of procedures. At least on every health plan I have had, that's the way it was. I chose HMO because I usually go in for checkups only and don't travel enough to warrant a wider area of coverage, and it saved me lots on premiums.