Seven patients with atrophie blanche or livedo vasculitis of the lower extremities showed abnormal platelet functions in vitro. Six of seven showed hyperaggregation with epinephrine and/or collagen, three showed increased platelet adhesiveness, three showed increased platelet count, and one showed increased microemboli. After treatment with dipyridamole and aspirin, all showed return to normal platelet function. Clinical improvement occurred in all patients, with significant alleviation of pain and decrease in new lesion formation. Although enhanced healing of lesions seemed evident to physician and patient, it was incomplete. In two patients, pain returned when dipyridamole and aspirin were stopped, but the patients improved again when the medicines were restarted. These preliminary findings indicate a possible beneficial effect of antiplatelet therapy in atrophie blanche and livedo vasculitis. A double-blind study is being undertaken to further study this effect.