In an open study that was conducted in general practice, 22 patients with previously-untreated mild hypertension received an average daily dose of 11.7 mg of pindolol over a 50-week study period. The total cholesterol, high-density lipoprotein fraction and plasma triglyceride levels showed no significant change from baseline values at the conclusion of this period. A separate group of 18 patients were treated with 10 mg of pindolol a day for 12 weeks, to which regimen was added 5 mg of clopamide for the succeeding 38 weeks. A small rise in total plasma cholesterol levels in this group of patients at both 12 and 50 weeks did not achieve statistical significance, and no change was observed in either the high-density lipoprotein fraction or the plasma triglyceride levels. These results which were obtained in general practice and over a prolonged period of time accord with the general view that the treatment of hypertension with pindolol, a beta-receptor blocking drug with partial agonist activity, is not associated with either the increases in total plasma cholesterol levels or the falls in the high-density lipoprotein fraction that have been reported with other beta-blocking compounds.