The new nonergot dopamine agonist CV 205-502 appears to be a promising alternative in the treatment of hyperprolactinemia. Regarding the potential use of CV 205-502 in infertility practice, we studied the influence of CV 205-502 on the return of endocrine fertility parameters during the physiological hyperprolactinemia of the puerperium. The resumption of pituitary and ovarian activity in 18 CV 205-502 treated women was compared with that in 10 bromocriptine-treated women. LH was measured by a new specific assay, which does not cross-react with hCG. This assay was also used in a second part of the study in which the pituitary function of 10 breast-feeding women was investigated. Both dopamine agonists adequately suppressed PRL. Pituitary secretion returned in the second week and was initially characterized by a high FSH/LH ratio. There were no major differences between CV 205-502 and bromocriptine. Ovulations occurred from day 18 on. The PRL rebound at the end of treatment seemed to play a role in the ovulation process. An acute increase of PRL just before midcycle was able to prevent ovulation. Breastfeeding women showed a delayed return of pituitary secretion: after a hypogonadotropic period, FSH returned in the third week and was followed by a period with a high FSH/LH ratio and follicular inactivity.