In order to assess the action of prolactin on the puerperal pituitary-ovarian resistance to physiologic stimulation, a study was conducted in 27 women divided into three croups. Group 1:9 postpartum women who did not wish to breastfeed their infants and received 2.5 mg bromocriptin (CB 154) twice daily for 14 days starting immediately after delivery: Group II: 9 normally lactating mothers; and Group III: 9 women with hyperprolactinemia associated with amenorrhea. The three groups underwent stimulation with LHRH and Pergonal 500. Results indicate lack of prolactin dependence in the pituitary-ovarian resistance of the puerperium. The possible mechanisms involved in the anovulatory period of lactation arc discussed.