Fatal pulmonary embolism caused by streptokinase treatment of deep venous thrombosis of the leg? During the last 10 years, four of 150 (2.7%) patients with deep venous thrombosis (DVT) treated with streptokinase (SK) at our department have died of pulmonary embolism (PE). A retrospective study of 1393 DVT patients treated with heparin during the period 1973-1986 showed that five (0.36%) of these patients died of PE while still on heparin. In this paper we describe the four patients treated with SK who developed fatal PE. In our opinion this increase in mortality does not warrant the use of SK in routine treatment of DVT of the leg before a proper trial has been conducted to compare the frequencies of pulmonary embolism after both treatments. 