The appearance of ovarian cysts during or before ovarian stimulation has been widely reported either in women undergoing pituitary suppression with GnRHa or in patients treated only with gonadotropins. The adverse effects of these cysts are still discussed. The management of patients who present ovarian cyst identified before superovulation remains controversial. When cysts are associated with GnRHa treatment, if E2 level is low, disregarding the cysts does not modify the outcome of IVF. If E2 level is high (ie. non desensitized patients) aspirating the cyst or postponing hMG treatment and continuing on GnRHa until the cysts regress and E2 levels decline provide the same results.