Following the casual observation reported by one anginal patient of ours, of improvement of its claudicatio intermittens with application of isosorbide dinitrate ointment directly on the leg suffering pain, we undertook a study to assess the possible use of the drug in peripheral vascular disease in a group of 10 patients suffering of a severe form of claudicatio intermittens. The effect of the drug was tested 1) by the subjective valuation of the patient itself 2) by treadmill stress tests performed at constant rate. In this case were used as reference parameters the distance walked without any symptoms and the maximal distance reached by each patient. The treadmill stress test was performed in basal condition and after longterm administration of isosorbide dinitrate ointment 100 mg three times a day for 30-45 days. In 5 patients the control test was repeated twice in different days to evaluate the reproducibility of the measure that resulted good, while other 5 patients performed the test one hour following the application of the drug in order to assess a possible acute effect of the drug that was not present in any patient. All the patients noted an improvement in their walking capacity but only after 15-20 days of treatment. In basal condition the distance walked without any symptoms by the patients was on the average m. 51 (+/- 52) and the maximal distance reached was m. 143 (+/- 111), while after the treatment were m. 151 (+/- 136) and m. 384 (+/- 203) with a difference highly significative (p less than 0.05 and p less than 0.01 respectively). From our data although preliminary, it is apparent that longterm local application of isosorbide dinitrate is effective in the treatment of patients with peripheral vascular disease and that the action of the drug seems to be related to a local effect.