The possibility that previously described effects of ethyl alcohol on peripheral endocrine glands might be mediated via pituitary prompted this investigation on the effects of ethanol on anterior pituitary secretion. Nine healthy male subjects were given beverage containing ethanol (1.5 g/kg) or beverage alone per os in a randomized cross-over study and plasma ACTH, FSH, GH, LH and TSH were measured by specific radioimmunoassays up to 15 h and the urinary levels of adrenaline and noradrenaline by fluorometry. A combined LRF and TRF test was also carried out in similar series of experiments. During the whole experiment there were no significant differences in the plasma levels of ACTH, FSH and TSH or in the urinary levels of adrenaline and noradrenaline between ethanol treated and control subjects. Plasma FSH, LH and TSH responses to LRF and TRF stimulation were also similar in alcohol treated and control subjects. Plasma ACTH values were high (113-270 pg/ml) both in control and ethanol experiment suggesting that the subjects experienced apprehension toward the experiment. Plasma GH level exhibited a non-sleep related burst in the late evening (from 0.4 ng/ml at 6 p.m. to 3.1 ng/ml at 10 p.m., p less than 0.01). This increase was not seen after alcohol ingestion (p less than 0.01). Plasma LH levels were significantly lower after 6 and 13 h in alcohol treated subjects than in controls (65 vs. 106 ng/ml, p less than 0.01 and 74 vs. 121 ng/ml, p less than 0.05 respectively). Because ethanol had no effect on the resting level of plasma GH or on the LH response to LRF, WE SUggest that ethanol exerts these effects on a suprapituitary site.