32 patients (mean age 65 years, range 51-75 years) were included in this controlled, double blind study to evaluate the effect of dipyridamole in patients with intermittent claudication. Following a run-in phase of one month, 15 patients received 400 mg dipyridamole per day and 17 patients placebo. Patient characteristics (risk factors, age, clinical and apparative tests) of both groups did not differ significantly before and during the study period. Mean pain free und absolute walking distance on the treadmill (3.2 km/h, 12.5 degrees gradient) increased significantly in both groups during study period (p < 0.001 and p < 0.01). Explanations are more intensive physical activity and increasing adaptation to treadmill exercise. However, dipyridamole did not induce a significantly longer walking distance in comparison with placebo. The working hypothesis that the drug with inhibiting properties of thrombocyte function prolongs walking distance in intermittent claudication, could not be confirmed.