This prospective double-blind randomized study examined the effect of verapamil on restenosis after angioplasty of renal artery stenoses. 31 patients received placebo or 120 mg verapamil two or three times daily until the appointed day of the control angiography after 3 months. All patients received 1.5 g aspirin per day. In the control group (13 stenoses, 12 patients) the degree of stenoses increased from 35 +/- 15% immediately after PTA to 41 +/- 21% at repeat angiography 3 months after PTA, in the verapamil group (20 stenoses, 14 patients) from 35 +/- 16% to 43 +/- 22% (ns). Stenoses recurred in 23% of the stenoses in the placebo group and in 20% of the stenoses in the verapamil group (ns). 5 patients, who interrupted the therapy, were excluded from the evaluation. In the conclusion, verapamil does not decrease the incidence of restenosis after PTA of renal artery stenoses during concurrent therapy with aspirin.