Numerous attempts have been made to prevent late restenosis after successful percutaneous transluminal coronary angioplasty (PTCA), but there is still no effective treatment. This report describes the effect of an oral lipid-lowering agent, pravastatin, on restenosis after successful PTCA. Sixty-six patients who underwent successful elective PTCA were assigned to a pravastatin-treated group (Group 1, n = 29) or an untreated group (Group 2, n = 37) in a prospective and randomized fashion. Pravastatin (5 mg or 10 mg twice a day) was given to Group 1 patients from day 3 after the procedure. Selective coronary angiography was repeated 3 to 5 months later, or sooner if the patient developed angina pectoris. The serum cholesterol level was decreased significantly in Group 1 (from 215.7 +/- 44.3 mg/dl to 181.2 +/- 30.3 mg/dl, p < 0.001), but not in Group 2 (from 191.9 +/- 30.8 mg/dl to 191.8 +/- 33.3 mg/dl, p = ns), at the time of repeat coronary angiography. However, there were no differences between the groups with regard to the recurrence of angina, the need for repeat PTCA, or restenosis, as assessed by quantitative analysis of coronary cineangiograms. These results suggest that oral pravastatin therapy does not effectively prevent late restenosis after successful PTCA by this mode of administration.