Recruits in the first month of basic training at Fort Dix, NJ and special forces personnel anticipating imminent combat in Vietnam showed lowered excretion of testosterone, epitestosterone, androsterone, and etiocholanolone. This suggests that men responded to the potential threat of these situations with an inhibition of testosterone secretion. The wide range of values, similar to that observed for 17-OHCS excretion, reflects the importance of individual differences in response and adaptation. The relative decrease in sexual activity experienced by men in these environments may have contributed to the lowered excretion of the androgen metabolites. The parallel fall in the excretion of 17-OHCS and C19O2 and C19O3 metabolites in the Vietnam group provides evidence of psychological adaptation rather than a shift in adrenal secretory or metabolic pathways in response to exposure to more chronic stress.