Long-term bromocriptine treatment was discontinued in thirty-seven women with hyperprolactinaemic amenorrhoea. After cessation of therapy thirty of the thirty-seven women became hyperprolactinaemic again with amenorrhoea or anovulatory bleeding. Seven of the women continued to have regular ovulatory menstruation but only three were normoprolactinaemic 3 months after stopping treatment. Two of the seven women had evidence of pituitary tumour regression. After the discontinuation they had nearly normal prolactin levels but during 2 years of follow up the serum prolactin levels slowly increased. In the twenty-seven women with pre treatment prolactin levels below 100 micrograms/I there was no difference between the prolactin levels before starting and 1 month after stopping treatment, while the women with pretreatment prolactin levels above 100 micrograms/l had lower levels after therapy. Bromocriptine treatment seldom results in permanent cure of hyperprolactinaemic amenorrhoea.