It is unknown whether the addition of dipyridamole to aspirin as pretreatment for patients undergoing percutaneous transluminal coronary angioplasty (PTCA) decreases acute complications. In this study 232 patients were prospectively randomized to receive either aspirin 325 mg orally 3 times daily (group 1, n = 115) or aspirin 325 mg orally 3 times daily plus dipyridamole 75 mg orally 3 times daily (group 2, n = 117) before elective PTCA. All clinical, angiographic and PTCA-related variables were similar between groups. Angiographic success rate was 93% in both groups. Clinical success was achieved in 107 patients (92%) in group 1 and in 101 patients (88%) in group 2 (difference not significant). Q-wave myocardial infarction occurred in 2 patients (1.7%) in group 1 and 5 patients (4.3%) in group 2 (difference not significant). Emergency coronary artery bypass grafting was required in 3 patients (2.6%) in group 1 and 7 patients (6.1%) in group 2 (difference not significant). There was 1 in-hospital death (in group 2). In this study, the addition of dipyridamole to aspirin as pretreatment of patients undergoing PTCA did not significantly reduce acute complications compared to aspirin alone.