Semen quality and serum testosterone were studied in six men with hypoprolactinemia (≤ 6 ng/ml) and in normoprolactinemic controls. The incidence of hypoprolactinemia in 92 men attending an infertility clinic was 7.5% Males with hypoprolactinemia showed in high percentage of disorders (oligozoosper-mia, 50%; asthenospermia, 75%; hypofunction of seminal vesicles, 67%; and hypoandrogenism, 67% Hypoprolactinemia is a clinical disorder associated mainly with poor sperm motility. © 1989 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.