Long-acting bromocriptine (Parlodel LAR) was used for treatment of 25 patients with acromegaly during the period of 3 to 24 months. Even after the first intramuscular injection of 50 milligrams of the drug a decrease in growth hormone (GH) concentration by at least 50% of the initial values was observed in 28% of patients and an improvement in a sense of well-being in 44%. After 6 months of administration of 100 mg of Parlodel LAR at intervals of 28 days a decrease in GH level by at least 50% was observed in a larger percentage of patients (36.8%), and in 10.5% of them there was a fall of GH concentration to below 10 microU/ml. Side effects, like nausea, vomiting and orthostatic hypotony, appeared within several hours after the injection of Parlodel and lasted in most cases up to 24 hours. After consecutive injections of the drug the side effects were of lesser intensity or completely disappeared. The results obtained allow to conclude that Parlodel LAR is an effective drug in some cases of acromegaly. In most patients the therapeutic effect can be seen after the first injection, but in some cases it appears only after several months of treatment.