Although the role of biogenic amines in the regulation of gonadotropin release has been studied extensively, the precise role of dopamine (DA) in stimulating LHRH and/or LH release is still controversial. In the present study 6 eugonadal women, aged 20-30, were given an LHRH infusion on day 6 of the menstrual cycle and the pattern and magnitude of LH and FSH responses were estimated. On day 6 of the next cycle, the experiment was repeated and DA was also infused beginning 60 min after the start of the LHRH infusion. Following LHRH infusion plasma LH showed a marked and significant rise with a mean peak increment at 4 h, and with a cumulative response (CR) of 9136 +/- 955 mIU/ml/6h. The pattern of FSH response tended to parallel that of LH; however, mean peak increment at 4 h and a CR of 2640 +/- 169 mIU/ml/6h were markedly lower. Plasma prolactin levels remained unchanged. Addition of DA to LHRH at 60 min evoked a significantly greater mean peak LH increment at 4 h and a CR of 15514 +/- 1836 mIU/ml/6h (p less than 0.001). There were no significant changes in either mean FSH peak at 4 h or in the CR (3257 +/- 309 mIU/ml/6h). As expected, a highly significant (p less than 0.001) decrease in circulating PRL from 12.1 +/- 3.1 to 3.0 +/- 1.5 ng/ml was seen during DA infusion. In conclusion, DA given by iv infusion enhancement LH response to LHRH in eugonadal women under the conditions of the present investigation, supporting a role for a dopaminergic component in the control of LH release in women.