The introduction of radioimmunoassay for prolactin concentrated interest in infertility research on prolactin-producing pituitary adenomas (prolactinomas). In women in the fertile age group these tumors cause amenorrhea and galactorrhea, and in men loss of libido, impotence and occasionally gynecomastia. Microprolactinomas (diameter 10 mm and less) and macroprolactinomas (diameter more than 10 mm) differ in growth characteristics, symptomatology and prognosis. Different therapeutic approaches may be used. Both bromocriptine treatment and selective microsurgical tumor extirpation are successful. Both have advantages and disadvantages, thus rendering the decision as to appropriate treatment increasingly difficult. Recent findings demonstrate that bromocriptine may cause irreversible tumor fibrosis, which decreases the chances of prolactin normalization by subsequent surgery.