This study investigated the preventive effect of pravastatin on restenosis following successful transluminal coronary angiography (PTCA) in 109 consecutive patients. Patients were randomly and prospectively assigned to the pravastatin group (group P, n = 57) or the control group (group C, n = 52). The former received 10 mg/day pravastatin from the day of PTCA for 3 months. Restenosis was defined as a > or = 50% diameter stenosis at follow-up angiography with a > or = 15% reduction in luminal diameter compared to post-PTCA. The effect of pravastatin was analyzed in association with 7 clinical and 15 angiographic factors. Follow-up rate, serum lipid levels (total cholesterol, triglyceride, and HDL-cholesterol), and clinical and angiographic backgrounds except age and angularity of the lesions were not significantly different between the two groups at PTCA. Three months later, total cholesterol decreased from 222.3 +/- 35.1 to 179.2 +/- 31.2 mg/dl in group P, but was unchanged in group C (from 226.0 +/- 33.7 to 211.7 +/- 30.9 mg/dl). The restenosis rate was not different between the two groups (35.6 vs 35.7% per patient, 32.0 vs 33.3% per lesion). Moreover, no relationship between restenosis rate and serum total cholesterol level at follow-up angiography was observed. Multivariate analysis, including 7 clinical and 15 angiographic factors, found neither pravastatin administration nor serum lipid levels were significantly correlated with decreased luminal diameter. Pravastatin (10 mg/day) did not reduce the incidence of restenosis after PTCA when administered from the day of PTCA for 3 months.