Some infertile patients who need IVF-ET for conception have small ovarian cysts diagnosed in pelvic ultrasonography. It is well known that it is impossible or very difficult to perform controlled ovarian hyperstimulation(COH) for such patients because of the poor ovarian response or the possibility of ovarian hyperstimulation syndrome(OHSS). To remove or to decrease the size of ovarian cysts, estrogen and progesterone (E-P) therapy with oral contraceptives for 2 cycles and transvaginal aspiration of ovarian cysts using transvaginal ultrasonography were performed in 36 IVF-cancelled infertile patients with ovarian cysts from February to October, 1988 at Seoul National University Hospital. Thirty-nine ovarian cysts($32.8{pm}9.6$mm in mean diameter) were treated with E-P therapy, and their size decreased to $28.2{pm}11.0mm$ after 1 cycle and significantly to $24.8{pm}14.7mm$ after 2 cycles. After E-P therapy for 2 cycles, 7(17.9%) ovarian cysts disappeared in ultrasonography, 9(23.1%) decreased in size significantly, 18(46.2%) had no change in size and 5(12.8%) increased in size. Thirty-two ovarian cysts($30.2{pm}9.7mm$) in 30 patients were aspirated transvaginally, and there was no significant decrease in size after follow-up transvaginal ultrasonography($27.8{pm}12.5mm$). After transvaginal aspiration, 3(9.4%) ovarian cysts disappeared and 28(87.5%) had no change in size. The mean amount of the transvaginally aspirated cystic fluids was $19.6{pm}13.2ml$, and there was no malignant cells in aspiration cytology. Four endometrioid cysts, one dermoid cyst and one mucinous cyst could be diagnosed in consideration of the findings of transvaginal ultrasonography and the characteristics and cytology of aspirated fluids. Therefore E-P therapy and transvaginal aspiration of ovarian cysts had made it possible to restart IVF program earlier in the IVF-cancelled patients with ovarian cysts.