Between 5 and 10% of all young girls and women suffer of severe primary dysmenorrhoea which interfers monthly with their activities. In this type of primary dysmenorrhoea we found hyperprolactinemia in 13 of 15 women who were examined. All 15 patients had a pituitary tumour ruled out and were treated with Bromo-ergocryptine (parlodel). Eight patients became free of symptoms and five were well improved. The possible correlation of hyperprolactinemia to premenstrual tension and severe primary dysmenorrhoea is discussed.