In order to evaluate the effects of low-dosage, 6-12 months course of oxandrolone treatment in constitutional delay of growth, we compared the growth responses on treatment, the pattern of sexual development and pubertal growth events, up to final stature of 11 prepubertal boys, aged 10.6-14.1 yr, with those of 11 prepubertal, age-matched untreated controls. Treatment caused a significant increase of height velocity, from 4 to 9 cm/yr, and a significant acceleration of bone maturation, without affecting the timing of onset of puberty, the progression of sexual development or the onset of pubertal growth spurt. On the other hand, oxandrolone induced an earlier skeletal growth arrest but did not affect the expected final height. Treated boys showed an adult stature not significantly different from that of control subjects. Our data suggest that 6 months-1 year, low dosage oxandrolone treatment in constitutionally delayed growth has no significant effect on the pattern of pubertal growth, nor on the rate of sexual maturation or on final height.