Corpsman train as soldiers as well as medical technicians, and serve alongside both Navy and Marine forces. They work in medical settings in the field, in military hospitals and in medical clinics and ships. In many instances, particularly in active combat zones, corpsmen are the first responders for injured soldiers.

Fleet Marine Medical Officers (FMMOs) are medical experts for Marine Corps Commanding Officers. They are in charge of medical readiness and the supervision of Independent Duty Corpsmen (IDCs), physician assistants, and Hospital Corpsmen. They provide patient care, patient tracking, and field trauma care and resuscitation.