When acute massive pulmonary embolism is life threatening, thrombolysis could be a therapeutic option. However, lysis may be contraindicated once the risk of bleeding is high. We report on two patients who have massive pulmonary emboli complicated by severe hypotension, justifying thrombolytic treatment. Nevertheless, recent surgery in the first patient and a fresh hemorrhagic duodenal ulcer in the second patient precluded thrombolytic treatment at the usual dosage. Therefore, prolonged lysis with low-dose urokinase (1,000 units/kg/h) was initiated. After a few hours, the patients became hemodynamically stable and inotrope/vasopressor doses could be reduced and stopped. No major bleeding was observed. Consequently, prolonged thrombolysis with low-dose urokinase could be an alternative approach to therapy in patients with massive pulmonary emboli when recommended thrombolytic dosages are contraindicated.