Pruritus is a common symptom among patients undergoing long-term hemodialysis. The effect of nicergoline, an ergoline, on pruritus was studied in products released during dialysis. In a first experiment series, 20 age-matched normal individuals, 25 patients receiving hemodialysis without pruritus, and 15 patients receiving hemodialysis with pruritus had intradermal tests with 500 micrograms of papaverine. All patients with pruritus had a small papaverine skin test response, and mean values were significantly (p less than 0.0001, Mann-Whitney U test) smaller in patients with pruritus. All patients with pruritus entered in a crossover, double-blind trial with nicergoline. In a first period of six dialyses, they received either nicergoline (daily oral dose, 30 mg, and intravenous dose during dialyses, 5 mg) or placebo. In the second period of six dialyses, patients received the crossover treatment. Nicergoline was effective in 13/15 patients, eight of these patients having a complete remission of pruritus. When nicergoline was stopped, patients relapsed within 24 to 48 hours. All patients who improved during the trial were then treated with a daily dose of 30 mg of nicergoline for 6 months. Seven patients had a complete remission, five had moderate symptoms, and one patient relapsed. This study demonstrated that some hemodialyzed patients with pruritus of unknown etiology had improvement with nicergoline.