The plasma or serum concentrations of GH, TSH, LH, PRL, testosterone, cortisol, T4, and T3, and the values of the T3 uptake test were monitored in 12 healthy male volunteers for a period of 20 h after administration of one large dose of ethanol (1.5 g/kg BW). The effects of TRH and LRH on the secretion of TSH, PRL, and LH were studied in these subjects once during the period of acute alcohol intoxication (4 h after the start of drinking) and once during the hangover period (14 h after the start of drinking). Each subject served as his own control by drinking water only during another experimental session. Alcohol had no significant effect on basal concentrations of GH, TSH, LH, T4, T3, or testosterone. The concentration of cortisol in plasma was elevated during the whole 20-h period after ingestion of alcohol, as compared with the control values. Alcohol also did not significantly alter the effects of TRH and LRH on plasma TSH and LH levels at 4 and 14 h. During the hangover period, the PRL response to TRH was totally blocked, but during alcohol intoxication, there was a slight increase in the PRL response to TRH. The lack of response of PRL to TRH during the hangover suggests that withdrawal symptoms are associated with increased dopaminergic activity in the hypothalamus.