Basal levels of serum thyroid‐stimulating hormone (TSH). T3, T4, free T3 and free T4 were measured in 40 chronic alcoholic men and in 31 normal volunteers. Their serum TSH responses to provocative thyrotropin‐releasing hormone (TRH) stimulation were then examined serially: in chronic alcoholics, every 5 days for a total of 3 studies; in 25 of the normal volunteers, before and 72 hr after daily ingestion of ethanol (2 cc/kg/day). Basal serum TSH levels were increased in the alcoholic men (3.5 ± 0.2 μU/ml) (mean ± SEM) compared to those of the normal controls (1.7 ± 0.1) (p < 0.01). Both basal serum T3 and T4 levels (T3, 0.89 ± 0.10 ng/ml; T4, 7.0 ± 0.4 μg/dl) were reduced in the alcoholic men when compared to those of the normal controls (T3,1.20 ± 0.03 ng/ml; T4, 8.6 ± 0.3 μg/dl) (p < 0.01 and p < 0.05, respectively). Basal serum free T3 levels were reduced in the alcoholic men (169 ± 22 pg/dl) compared to the normal controls (380 ± 18) (p < 0.01). In contrast, basal serum free T4 levels were increased in the alcoholics (4.0 ± 0.2 ng/dl) compared to those of the normal controls (2.9 ± 0.1) (p < 0.01). In response to TRH, the serum TSH levels of the alcoholic men achieved a peak of 13.5 ± 0.9 μU/ml compared to 14.9 ± 0.9 for the normal controls (no significant difference). Despite better nutrition and alcohol abstinence associated with hospitalization for 10 days, no improvement in either the basal levels of TSH, T3, and T4 or the TSH responses to provocative TRH was observed in the alcoholic men studied. In normal volunteers, ethanol had no effect on the basal or TRH‐stimulated levels of serum TSH and thyroid hormones.