I've looked into this quite a bit. It varies from school to school, but most schools have you pay full med school tuition and then give you a big discount on your MPH tuition if you do it while you are a medical student at that university.
The option where you get the MPH paid for completely is after you complete your residency. Most public health schools are glad to have a fully certified doctor in their program, it makes them look good, so they will often waive tuition and even give you a living stipend similar to residency pay. This sounds appealing at first, but not many students do it. After you finish residency you have the choice to go out and make six figures, doing what you've trained 80 hours per week for four years to do, or go to MORE SCHOOL. Most people choose working over an MPH, so the PH schools have to at least offer a nice stipend to get anyone interested. I do know people who have done this later in thier careers though, just for a change.
