BACKGROUND: Thrombolytic agents have been used successfully to treat patients with massive pulmonary embolism and cardiorespiratory insufficiency, but experience with these drugs in pregnancy is limited. CASE: A 20-year-old woman at 21 weeks' gestation was admitted with a massive pulmonary embolism. She was initially given intravenous heparin therapy but because of worsening clinical condition, urokinase was used. After two 12-hour periods of therapy, the urokinase was discontinued and the heparin restarted. She remained on subcutaneous heparin therapy for the remainder of her pregnancy, which was otherwise uncomplicated. She delivered a healthy male infant at term without complications and was discharged on warfarin therapy. CONCLUSION: Thrombolytic therapy can be life-saving and should be considered in the treatment of hemodynamically significant pulmonary embolism in pregnancy.