CV 205–502 is a nonergot oral dopamine agonist with specific D2 activity, which has a prolonged suppressive effect on serum PRL and may have fewer side-effects than other dopamine agonists. We treated 26 hyperprolactinemic women with this compound given as a single bedtime (hs) dose for up to 12 weeks. All had gonadal dysfunction, either amenorrhea or oligomenorrhea, and 15 had galactorrhea. The initial and subsequent doses were administered in a randomized fashion; the initial dose ranged from 0.01–0.05 mg, and the dose at 12 weeks ranged from 0.03–0.09 mg. The women were evaluated every 2 weeks, and the dose was increased by 0.02 mg every 4 weeks if the serum PRL level was greater than 20 μg/h. Of the 26 women initially enrolled, 24 completed 12 weeks of therapy, and 2 discontinued therapy because of side-effects. Thirteen women (54%) had return of menses, and 12 (80%) had either a decrease in or disappearance of galactorrhea. Serum PRL concentrations decreased to a variable degree in all patients; 13 (54%) achieved a normal serum PRL level (≤20 ±g/h). The mean (± se) pretreatment serum PRL concentration was 129 ± 34, and it was 29.9 ± 5.9 ±g/L after 12 weeks of treatment (P = 0.005). The mean (±se) percent reduction in serum PRL was 66.5 ± 5.0% (median, 78.0%). A dose response was not demonstrated (r = −0.08; P = 0.70) among the 6 dose groups during the last 4 weeks of therapy. In 5 women, serum PRL levels, measured frequently for 24 h after treatment remained low. Side-effects after the initiation of therapy included nausea, headache, and morning fatigue in 10 women. These symptoms caused 2 women to discontinue therapy; they subsided in the other women. An optimal dose was not determined and will probably need to be determined by titration in each patient. CV 205–502, given once daily, appears to be a safe and effective alternative to other dopamine agonists in the treatment of hyperprolactinemia. © 1989 by The Endocrine Society.