The pubertal growth spurt is based on synergistic effects of hGH and androgenic steroids. It fails to appear in androgen deficiency as well as in complete absence of hGH. Apart from the synergism of biological functions there are interactions with regard to the secretion of hGH and androgens. Investigating the nocturnal hGH-secretion in puberty stage 3 we found twice as high secretion rates as in stage 1. Children with anorchia or constitutional delay of growth and adolescence during treatment with testosterone secreted more than threefold amounts of hGH as before. In two cyproterone acetate-treated adolescents, and in four 12-19 years old patients with hypogonadism, the nocturnal secretion rates of hGH as well as the maximal hGH-peaks attained were lower than in normal prepubertal children. The conclusion is drawn that the androgen-secretion during adolescence is not only prerequisite to the hGH-increment necessary for the pubertal growth spurt but also to the preservation of basal hGH-secretion.