HM3 stands for Hospital Corpsman, Third Class in the Navy. A medical professional enrolled in the US Navy is known as a corpsman.
On land and in the sea, Naval Hospital Corpsmen support the Marine Corps and the Navy.
The Rules for the Regulation of the Navy of the United Colonies of North America, which describes setting up a distinct facility for the care of the sick and injured, contains the earliest known documented reference to the organisation of Navy medicine. Naval medicine has a lengthy history.
Women were accepted into the Hospital Corps during World War II and given the designation WAVES.