The appearance of petechiae and ecchymoses following anticoagulant and fibrinolytic therapy is an unusual and rare complication. The mechanism of the vasculitis is obscure but may be related to a chemical vasotoxic reaction. During anticoagulant and fibrinolytic therapy, 6 patients developed petechiae and ecchymoses which was accompanied by pain and fever. There were no disturbances of blood clotting factors. In spite of the varied action of the different anticoagulants and fibrinolytic drugs, the clinical course and the histological examination demonstrated a similar identical vasculitis.