The ovarian uptake of tritiated human chorionic gonadotropin (3H—hCG) in hypophysectomized rats was investigated and correlated with ovarian morphology after treatment with various combinations of gonadal and gonadotropic hormones. Neither estrogen nor progesterone enhanced 3H—hCG uptake. Both hCG and FSH doubled 3H—hCG uptake. Maximum stimulation of 3H—hCG uptake was seen, however, only when corpus luteum formation followed administration of either hCG and FSH given together or PMSG given alone. (Endocrinology92: 1565, 1973)