Synotinatuc subclavian vein thrombosis developed in a patient receiving long-term parenteral nutrition. Serial phlebograms showed progression of venous thrombosis, despite therapy with heparin. Fibrinolytic therapy with streptoikinase, monitored in the laboratory by the euglobulin clot lysis time, was strikingly successful and may be the treatment of choice for this condition if certain contraindications are absent.