Fetal and neonatal hypoadrenalism was induced by treating rat mothers with metyrapone from day 12 of pregnancy to day 7 postnatally. Hypoadrenalism in the neonates was indicated by a slight reduction in body weight, adrenal hyperplasia and a tendency towards reduced adrenal corticosterone concentration. An intraperitoneal glucose tolerance test on the 7-day old neonates did not show any disturbancies of glucose disposal or insulin secretory response to glucose. The data suggest that adrenal corticosteroids are not essential for the perinatal development of the B-cell secretory response to glucose.