In the course of a clinical trial with 2alpha-bromoergocryptin in Parkinson's disease, the serum levels of several pituitary hormones have been studied in the assumption that the drug active on nigro-striatal dopaminergic system might also interfere with hypothalamus-protuberantial neurotransmission, and have effects on the function of the pituitary. No changes in serum levels of FSH, LH, STH and TSH were detected for every dose of the drug employed. Only prolactin serum levels diminished since the beginning of the treatment, the decrease being significant (p less than 0.05 and p less than 0.01). This effect on prolactin does not change in the dose range considered. Clinical improvement was observed for doses of drugs above 15 mg/day, whereas the effect on prolactin secretion occurred with the dose of 7.5 mg/day.