OBJECTIVE We studied whether the administration of oral contraceptives facilitates the disappearance of spontaneously formed functional ovarian cysts. METHODS Eighty patients in whom ultrasonography revealed unilateral, mobile, unilocular, thin-walled ovarian cysts without internal echoes and greater than 30 mm but not exceeding 60 mm in diameter were enrolled into the study. Patients were randomized by stratification to receive a low-dose monophasic pill, a high-dose monophasic pill, a multiphasic pill or no therapy. Patients were re-evaluated after 5 weeks of therapy and at the end of therapy (10 weeks). RESULTS The mean ages and the mean cyst diameters of the patients for each group were not significantly different. We did not find a significant effect of oral contraceptive administration on the disappearance rate of functional ovarian cysts over that of expectant management. CONCLUSIONS We conclude that oral contraceptive therapy even with multiphasic pills is very effective in the management of functional ovarian cysts but expectant management achieves similar success rates and may be a good alternative to oral contraceptive therapy.