The relationships between growth retardation and metabolic and hormonal parameters were studied in 7 children with fetal alcohol syndrome (FAS). Fasting blood concentrations of TSH, T4, T3, FSH and LH were normal. Plasma prolactin concentrations after chlorpromazine stimulation were normal. 3 children had abnormal oral glucose tolerance tests with increased plasma insulin response. Peak plasma growth hormone responses to insulin-induced hypoglycemia were elevated in 5 patients. Fasting bioassayable serum somatomedin activity, determined in 6 patients, was elevated in 3 patients and normal in 3 patients. Administration of hGH to 3 patients with FAS had little effect upon nitrogen retention and did not increase plasma insulin concentrations, although serum somatomedin activity sharply increased in 1 patient evaluated for somatomedin response. The data indicate that the growth defect in FAS is not due to deficiency of growth-promoting hormones, but rather to peripheral unresponsiveness.