Authors have disputed the classic normal ovarian volume measurement of 6 cm3 without reference to a study with a large number of patients. To determine normal sonographic measurements, 762 consecutive female patients were examined. Satisfactory measurements of 1,157 ovaries in 725 of these patients were obtained. Average ovarian volumes of 9.8, 5.8, and 3.0 cm3 were obtained for the menstruating, postmenopausal, and premenarchal groups, respectively. These volumes were significantly different for these three menstrual groups (P less than .0001). Significant volume differences were noted when measurements were grouped by decade of life. Volumes peaked in the 3rd decade and declined over the subsequent four decade groups. A significant average volume difference was noted between pregnant (11.1 cm3) and non-pregnant (9.4 cm3) menstruating patients (P less than .0001). No significant differences in volume were noted between right and left ovaries or when the variables of weight, presence of a leiomyomatous uterus, or phase of the menstrual cycle were evaluated.