The changes in plasma prolactin (PRL) concentrations were studied in 176 hyperprolactinemic women over periods of 6-180 months, to evaluate the independent effects of time, drugs and pregnancy on the evolution of prolactinemia. CT scans showed pituitary adenoma in 87 (9 macroadenoma), the clinical presentations for 110 patients there amenorrhea, for 37 abnormal cycles and 29 had anovulatory sterility as an isolated symptom. 107 women underwent 191 cycles of dopaminergic treatment and 73 had pregnancies (86), either spontaneously or as a consequence of the treatment. Changes in prolactin induced by medical treatment and pregnancy were recorded and the spontaneous changes in prolactin in 38 patients (17 with adenoma) were followed over periods of 6-72 months. Final mean PRL concentrations were lower than basal though not significantly, in both 'functional' (54.4 vs. 79.2 ng/ml) and prolactinoma patients (87.3 vs. 116.4 ng/ml). Separate calculation of changes in prolactin after the course of medical treatment, pregnancies or 'just waiting' periods showed mean PRL concentrations to be significantly lower only for 'functional' patients after pregnancy. On the other hand, PRL variations in individual patients revealed that: (1) spontaneously, PRL rarely becomes lower over a few years; (2) dopaminergic treatment was associated with normalization of PRL in 13% of women; and (3) pregnancy normalized prolactin concentrations in 29% of the patients. Chi-square analysis of the PRL-lowering frequencies in functional patients showed a high cure rate for pregnancy (P less than 0.0001) and a lesser but still significant effect of drugs (P less than 0.025).