Requirements vary based on the type of medicine a doctor would like to practice. However, all doctors must at least complete an undergraduate degree from a four-year college or university, plus four additional years of graduate school at an accredited medical school. Graduating from medical school is required for obtaining a Medical Doctorate degree (M.D.), or a Doctorate of Osteopathy degree (D.O.) based on the type of medical program you complete. Every medical school offers one of two approaches to medicine – Allopathic (M.D.) or Osteopathic (D.O.).