The aim of the study was to evaluate the short term and long-term effects of long acting repeatable bromocriptine (= Parlodel-LAR*) in patients with macroprolactinomas. Twenty-nine patients (15 men and 14 women) aged 42 +/- 2.7 (M +/- SEM) years were injected with Parlodel-LAR* every 4 weeks during 3.3 +/- 0.3 years. The starting dose was 50 mg/injection, then it was increased to 100 mg in 11 patients and 150 mg in 9 patients. PRL levels decreased in all but one patient 4 weeks after the first injection (270 +/- 59 vs 934 +/- 210 ng/ml, p < 0.001), then became less than 20 ng/ml in 20/29 (69%) patients and finally became undetectable or low in 13/29 (45%) patients. Visual field defects were present in 12/29 patients before treatment. In 11/12 patients, treatment with Parlodel-LAR* resulted in an improvement and complete correction of visual field defects was observed in 8/12 patients. Adenoma size (2.5 +/- 0.2 cm before treatment) was reduced by at least 20% in 24/29 (83%) patients. Disappearance of adenoma was observed on CT scan in 8/29 (28%) patients after 28.7 +/- 5.3 months of treatment. Minor side effects occurred in 20 patients after the first injection then disappeared in 18 patients within the following 6 months of treatment. One patient had rhinorrhea after 3 months of treatment. Treatment with Parlodel-LAR* results in beneficial short-term effects (with rapid correction of recent onset visual field defects) and long-term effects (which can include complete disappearance of adenoma on CT scan evaluation) in patients with macroprolactinomas.