Chronic GnRH analogs (GnRH-A) administration has proven to be effective for the control of some hormone-dependent tumors. GnRH-A are now in the standard treatment of prostatic cancer. In the present paper experimental and clinical data on the use of GnRH-A in gynecologic oncology are reviewed in order to identify a possible role in the therapy of breast, endometrial and ovarian cancer. Besides the indirect hormonal effect of GnRH-A, mediated by the suppression of gonadal steroidogenesis, in vitro evidence suggests a direct anti-proliferative action involving autocrine-paracrine regulation of cellular function. In advanced or recurrent breast cancer objective responses were observed in 157 out of 378 premenopausal patients (41%) and in 18 out of 166 postmenopausal women (10%). In ovarian cancer complete and partial responses were observed in 14 out of 121 (11%). At present, data on advanced endometrial carcinoma are limited: only 18 treated patients are reported, of whom 7 responded (38.8%). However, in general, most of the responses observed were transient. Thus, so far, the use of GnRH-A in gynecologic oncology has to be considered for palliation, after the failure of other better understood treatment modalities. The possible use of GnRH-A as an adjuvant is still under investigation.