The effect of metoclopramide on ovarian responsiveness to gonadotropin administration in patients with severe polycystic ovarian syndrome. Six patients with poor ovarian response to menotropin after pretreatment with a gonadotropin-releasing hormone analog exhibited improved ovarian responsiveness when metoclopramide was added on days 3, 5, and 7 of the cycle. This was evidenced by a higher number of leading follicles (4.4 versus 0.6), a higher mean of maximal serum 17 beta-estradiol levels (560 versus 178 pg/mL), a shorter duration of menotropin treatment (7 versus 11 days), and fewer ampules of menotropin used (20 versus 37 ampules/cycle) in metoclopramide-treated cycles as compared with control cycles, respectively. Serum prolactin levels reached a maximum of 172 ng/mL within 1 hour after metoclopramide administration and declined to normal range within 6 hours. These results suggest that intermittent increased prolactin secretion may augment ovarian response to gonadotropins. 