Prolactinoma is the most frequent type of secreting pituitary tumours. In the treatment, pharmacotherapy with dopamine agonists is considered the first-line option. For many years bromocriptine, a D1 and D2 dopamine receptor agonist, has been the standard medicine for hyperprolactinemic patients. However, the treatment is frequently associated with intolerance or resistance. Recently cabergoline, a long acting, ergoline-derived, selective D2 agonist has become available and has been promoted as the initial treatment. Therefore the object of four studies was to assess the efficacy and tolerability of cabergoline in patients with prolactin-secreting pituitary adenomas. 17 patients, 13 women at the age of 21-55 years (average 37.1) and 4 men at the age of 29-45 years (average 36.3), with pathological hyperprolactinemia due to pituitary tumours were involved in the study. In all patients the increased pretreatment concentration of PRL was observed, ranging from 1047 to 1678 mlU/ml (mean 1369 mlU/ml). MRI scans revealed microprolactinomas in 11 (64.7%) cases and macroadenomas in 6 (35.3%) cases. None of the patients had previously undergone pituitary surgery and all of them were newly diagnosed, previously untreated. The patients were treated with cabergoline for 6 months. Cabergoline therapy was started at a dose of 0.5 mg twice a week for the first two months, then the dose was decreased to a 0.25 mg twice a week and finally maintained at 0.25 mg a week. After 6 months of the therapy, the normalization of serum PRL concentrations (from mean 1358 mlU/ml to mean 420 mlU/ml; p < 0.001) was achieved in 13 (76.5%) patients (8 with microprolactinoma and 5 with macroprolactinoma). In the remaining 4 patients PRL levels remained elevated but were decreased from mean 1403 mIU/ml to mean 812 mIU/ml. There were no differences, regarding CAB efficacy in lowering PRL levels, between patients with micro- and macroadenomas (p > 0.05). About 90% women resumed menstrual cycles in our study. All the other clinical pretreatment symptoms disappear in the course of the therapy. The tumour shrinkage, confirmed by control MRI was noted in 2 patients (33%) with macroprolactinoma. Cabergoline was tolerated satisfactorily by all our patients. The results have confirmed a high efficacy and a very good tolerability of CAB in the treatment of patients with pituitary adenomas. Together with a very convenient administration, such therapy can provide a very good patient compliance thus should be considered the first line option in patients with prolactinomas.