The question of whether women are joining medical specialty societies at the same rate as their male counterparts has not been studied. A questionnaire was mailed to 48 medical specialty societies representing the 37 specialties listed in the Physician Characteristics and Distribution in the U.S., 1986 Edition. The response rate was 79%. Twenty organizations were able to identify the sex of their members, including the 7 specialty societies that represent the 6 most frequently chosen specialties of women physicians. Only in the American Psychiatric Association and the American Academy of Family Physicians was the enrollment of potential female members equivalent to that of male members. If the medical specialty societies do not address the issue of women being underrepresented in their societies, they will lose a large potential resource of leadership, participation, and financial support. More important, the societies will not be truly representative of their specialties.