Luteinizing hormone and FSH concentrations were determined in sera obtained from 20 males and 20 females, ages 5 to 16 years, with sickle cell anemia (homozygous hemoglobin S). Height, weight, bone age, and stage of sexual development were also determined. Gonadotropin concentrations were increased for stage of sexual development, suggesting transient impairment of gonadal function during the first decade of life. Increased impairment of growth during the second decade of life (18 of 26 subjects, 69%) as compared to the first decade (4 of 14 subjects, 29%) was consistent with prior deficiency of gonadal secretion of steroids. Mean bone age (11.2 +/- 2.1 year) determined in 15 subjects was significantly less than the mean chronologic age (13.0 +/- 1.8 year). Significant additional data, particularly those which would be derived from a longitudinal study, are needed to validate the preliminary hypothesis that transient impairment in gonadal function may, in part, account for the variation in sexual maturation seen in subjects with sickle cell anemia.