This study was performed on 8 patients with normal levels of PRL and ovulatory cycles. Three of these patients were treated with 5 mg/day Bromocriptine and three of them with 60 mg/day Metoclopramide from the beginning of the cycle in order to induce hypo- and hyperprolactinemia respectively. The other two women were left as control. Daily blood samples were collected for the determination of PRL, LH 17 beta-Estradiol and Progesterone. Patients were operated on between the 6th and the 8th day after the LH peak and corpora lutea enucleated and frozen for subsequent 125I-LH binding tests. An analysis of our data demonstrates that hypo- and hyper- prolactinemia induced with Bromocriptine and Metoclopramide respectively may cause luteal insufficiency, which is revealed by decreased blood levels of progesterone. Furthermore we have observed that specific binding for LH in human luteal tissue is always present (in normal, hypo- and hyperprolactinemic women) but is reduced in presence of very high or very low levels of PRL.