Abstract: An apparatus for exercising muscles of a female patient's pelvic diaphragm, most particularly vaginal wall muscles. A slickened elastomeric elongated balloon with a cylindrical wall and a first closed end is provided. Latex for example is a suitable elastomeric material for this application. The cylindrical wall has sufficient rigidity for the balloon to be inserted closed endwise into the patient's vagina, without need for any stem member. The second end of the balloon reduces in section to form a shoulder and a tube adapted to extend out of the patient's vagina. A collar surrounds the tube and abuts the shoulder so that the patient can manually hold the balloon in her vagina. In an alternate embodiment, the tube is stiffened. The balloon may be filled with a fluid, such as air, another gas or a liquid (at atmospheric or superatmospheric pressures) and measurements of pressures in the balloon index exertions of the muscles of the patients' pelvic diaphragm.