OBJECTIVE To determine the frequency with which hyperprolactinaemic illness tends to resolve with time. METHODS A retrospective case-notes review from a specialist endocrine unit in a provincial teaching hospital and tertiary referral centre. METHODS Seventy women with hyperprolactinaemia referred to the unit in the 15 year period between May 1979 and May 1994. All those with a non-pituitary cause or with macroadenoma had been excluded, as were those who did not have high-resolution imaging, or who were on treatment at the time of referral. METHODS Intermittent course of treatment with dopamine receptor agonists according to individual need. METHODS Latest serum PRL concentration in those who had discontinued treatment, and whether serum PRL tended to be lower in any particular group. RESULTS There was a significant fall in median PRL concentration from 2000 (714-8000) to 1000 mU/l (220-5600) in the 31 women who had discontinued therapy (P < 0.0005), and serum PRL was normal (< 700 mU/l) in 11 of them. Serum PRL also fell to normal in three of ten women who had no treatment at all. Final PRL concentration was normal in 35% of women who had had at least one pregnancy during the period of follow-up compared to 14% who had not (P < 0.05). CONCLUSIONS These data confirm the findings of others that hyperprolactinaemia will prove self-limiting in up to one-third of women, and that pregnancy may be one factor which triggers a return to normal function.