Medical school admissions are competitive, so you need to have a strong GPA. A GPA above 3.5 is preferrable. A GPA below 3.5 can somtimes raise a flag, especially if you attended a school famous for grade-inflation, like Harvard. While things might have changed a little at Harvard, there is still the impression that everyone gets a minimum 3.3, so the GPA cutoff might be more strictly enforced.