Effects of gonadotropin and LHRH on the cAMP levels, adenylate cyclase and cyclic nucleotide phosphodiesterase activities of the pineal, hypothalamus, pituitary, adrenal and ovary of the female pubertal rabbits were examined, and serum FSH, LH, estradiol and progesterone were measured. Gonadotropin and LHRH were injected intravenously five days, and 16 hours after the last administration, experiments were performed. The cAMP levels in the endocrine organs of the female pubertal rabbits were higher than adults. Gonadotropin and LHRH administration decreased the cAMP levels, i.e. draw to the levels of adults, in almost all endocrine organs. In pre-pubertal period (5-7 weeks of age), cAMP responses of hypothalamus and pituitary to gonadotropin or LHRH were significant, whereas responses of adrenal and ovary were slight and not significant. In early and mid-pubertal period (9-14 weeks of age), changes of the cAMP levels in the hypothalamus and pituitary were slight than pre-pubertal period, but in ovary, remarkable change of the cAMP levels were observed. The adenylate cyclase activities of all endocrine organs were not changed and the phosphodiesterase activities were increased by gonadotropin or LHRH administration. Serum FSH, LH estradiol and progesterone were increased with age. The most remarkable increases were occurred to the serum FSH level of pre-pubertal rabbits (7 weeks of age) after gonadotropin or LHRH administration, and serum progesterone of mid-pubertal rabbits (14 weeks of age) after gonadotropin administration.