Androgenic hormones were investigated during two separate 5-day military endurance training courses, with physical activities around the clock corresponding to a daily energy consumption of about 40,000 kilojoules, but with an intake of only 2,000 kilojoules. Altogether, the cadets slept for 1-3 h in the 5 days. Eleven male cadets participated in course I, and 10 in course II. Plasma levels of testosterone, free testosterone, dehydroepiandrosterone, 17 alpha-hydroxyprogesterone, and androstenedione decreased by 60-80% during the course. In contrast, plasma cortisol, aldosterone, progesterone, and dehydroepiandrosterone sulfate increased. LH, FSH, and ACTH decreased to about 50-80% of precourse levels. Weak correlations between plasma levels of hypophyseal and levels of adrenal and testicular hormones indicate a multifactorial regulation. In conclusion, both adrenal and testicular androgens decrease during prolonged physical strain combined with energy and sleep deficiency.