I just posted this in another thread so I hope it helps:
"I finished my interview about a week and a half ago, and was accepted to U of M's HMP Department yesterday. The MPH and MHA interviews days are coordinated together, so there was about 11 people that interviewed with me. Each person has a different schedule but the interview is fairly brief and depends on which faculty member actually interviews you. Some are more laid back, while others are more serious. My best advice is to just be confident about why you're there and what you want to gain from this program. Also be confident about what you as a student will add to the program. Dress nicely, be pleasant, and ask great questions because they are looking at you for the entire visit day, not just the actual interview. "