What were the roles of American women during the Vietnam war?

Mostly nurses, all volunteers, and part of the WACs, WAFs, and WAVES. Those latter units were disbanded in 1975 at war's end, and the new all volunteer equal-opportunity military took their place.

As women are historically prohibited from combat, they served in various non-combat roles, including doctors, nurses, mechanics, training officers, transport pilots (non-war zone) and numerous administrative positions in both military and government positions.