Several studies have suggested that a functional relationship exists between the adrenal gland and the ovary. The purpose of this study was to determine the effect of corticosterone on the sensitivity of the ovary to exogenous gonadotrophin. Sexually immature White Leghorn pullets, 18 weeks of age, were infused with 30 micrograms/hr of corticosterone for 14 days. After 7 days of infusion, the pullets were injected with 3, 15, 75, or 375 IU pregnant mare's serum gonadotrophin (PMSG) for 7 days. Controls consisted of noninfused pullets injected according to the same doses of PMSG. Blood samples were obtained on Days 3, 6, 8, 10, and 12 of infusion and were assayed for plasma concentrations of luteinizing hormone (LH), estradiol, and corticosterone by radioimmunoassay. The daily injections of 75 or 375 IU PMSG in noninfused pullets resulted in an increase in ovarian and oviductal weight and the formation of a hierarchy of yolk-filled follicles. This was accompanied by an increase in the plasma concentrations of estradiol and a decrease in the plasma concentrations of LH. The infusion of corticosterone significantly increased the plasma concentrations of this steroid over that observed in the control pullets and was not related to the dose of PMSG. This increase in plasma levels of corticosterone was associated with a significant decline in the plasma concentrations of LH and estradiol before the injection of PMSG. After 6 days of PMSG treatment, the plasma concentrations of estradiol increased to that observed in control pullets and was dependent upon the dose of PMSG injected.(ABSTRACT TRUNCATED AT 250 WORDS)