The serum levels of bioactive luteinizing hormone (LH), immunoreactive LH, follicle-stimulating hormone (FSH), and testosterone were determined in eleven anovulatory women with polycystic ovary syndrome (PCOS) before and after laparoscopic ovarian cautery. Before treatment, the mean ± SEM levels of bioactive and immunoreactive LH and testosterone were 53.1 ± 7.9 mlU/ml, 35.2 ± 3.9 mlU/ml, and 1.14 ± 0.13 ng/ml, respectively, which were significantly higher than those of five control women (19.2 ± 1.6 mlU/ml, 21.4 ± 1.2 mlU/ml, 0.28 ± 0.03 ng/ml). After treatment, the mean levels of these hormones decreased significantly, ten women ovulated spontaneously and four conceived. The present results suggest that decreases in the levels of these hormones by laparoscopic ovarian cautery in women with PCOS may result in both restoration of the ovulatory cycle and the achievement of pregnancy.