In this cross-sectional study, plasma levels of dehydroepiandrosterone sulfate (DHEA-S), dehydroepiandrosterone (DHEA), delta 4-androstenedione (delta 4) and testosterone (T) were measured by RIA in 232 normal subjects of both sexes, aged 2 weeks to 20 years. The results were analyzed in relation to chronological age, body surface and pubertal stage. High levels of plasma androgens were found in newborn infants of both sexes. After 3 months of age, androgen levels were uniformly low and rose with increasing chronological age and body surface. The first significant increase in mean androgen levels was found for DHEA-S. It occurred after 6 years of age in girls and after 8 years in boys. DHEA and T rose in both sexes after 8 years of age. delta 4 increased steadily with chronological age and body surface in both sexes. When androgen levels were related to body surface, a first significant increase was observed above 1.00 m2 for the four androgens, in both boys and girls. Above 1.20 m2 and 12 years of age, girls had higher mean levels of DHEA-S, DHEA and delta 4, but lower mean T levels than boys of the same body surface and chronological age. Before puberty, a positive correlation was found in both sexes between the plasma androgen levels on the one hand, and both chronological age and body surface on the other. Plasma androgen levels markedly increased at stage P2 in both sexes, and further increased with pubertal development. During puberty, girls had higher plasma delta 4, but lower plasma T levels than boys of the same pubertal stage. Plasma DHEA-S and DHEA levels were similar in both sexes. In contrast to the plasma androgens, plasma cortisol levels did not show any change in relation either to chronological age or to body surface or pubertal development. Body surface appears to be as good a discriminating factor as chronological age, at least in young children. It also appears from this study that DHEA-S is a good guide for the clinical evaluation of adrenal maturation and may be very useful in evaluating patients with growth or pubertal disturbances.