Ovarian laparoscopic resection was applied to 23 sterile patients affected with polycystic ovarian disease (PCOD) resistant to different pharmacological treatments, in order to induce ovulation. After resection, 56% of the patients had spontaneous ovulatory cycles and 13 pregnancies arose. Ten of the pregnancies were spontaneous and three followed treatment with clomiphene. Hormone changes were assessed in 15 patients, including five with spontaneous menstruation but without ovulation and five with persistent amenorrhoea for 3 months after resection. A significant decrease in both androstenedione and testosterone levels occurred in all patients. These decreases were not related to the clinical results of resection. Luteinizing hormone (LH) did not vary greatly in any group after resection. Mean values and mean pulsatility of follicle stimulating hormone (FSH) increased significantly only in pregnant patients or those with spontaneous ovulatory cycles. The results of gonadotrophin-releasing hormone (GnRH) assays did not change after resection. The mechanisms involved in the resumption of cyclic function of the hypophyseal-ovarian axis after resection are discussed briefly.