A 15-year-old girl referred because of primary amenorrhea was found to have a hypoplastic uterus and persistent hyperprolactinemia (72-110 ng/ml). The gonadotrophin-dependent pubertal signs, i.e. breast and vulvar development, were significantly retarded (Tanner stage 2-3) while sexual hair was well developed; bone age was 13 years. The endocrinological evaluation revealed gonadotrophin secretion (LH-basal: 0.85-1.25; peak after LH-RH: 10.4 mIU/ml; FSH-basal: 1.63-2.5; peak: 8.2 mIU/ml) and E2 levels (26-68 pg/ml) which were appropriate for Tanner stage 3. The high basal levels of PRL were nonresponsive to either stimulatory (TRH) or inhibitory (nomifensine) agents. CT scan of the brain suggested the presence of a pituitary microadenoma. Following therapy with bromocriptine (2.5 mg/day) plasma PRL levels dropped to normal (5-6.8 ng/ml) with an accompanying catch-up of pubertal development and linear growth and a marked increase in size of the uterus as documented by repeated ultrasonographic examinations. Menarche occurred 5 months after initiation of therapy, followed by regular menses thereafter. Repeated CT scan of the brain showed a decrease in the density and size of the still persisting lesion. This patient demonstrates that hyperprolactinemia can cause delayed puberty with a particular inhibitory effect on uterine growth and development.