The mainstay of treatment for massive pulmonary embolism in nonpregnant individuals is urgent thrombolytic therapy, but experience with these drugs in pregnancy is limited. We report a case of a 36-year-old woman at 27 weeks’ gestation who was admitted with a massive, life-threatening pulmonary embolism. The diagnosis was rapidly accomplished in the coronary care unit by transthoracic echocardiography that showed signs of pulmonary hypertension as well as a large, free-floating thrombus in the right heart. As she was hemodynamically unstable, we started treatment with tissue plasminogen activator resulting in complete resolution of cardiorespiratory symptoms. A live baby was delivered by Caesarean section at 37 weeks of gestation, and no complications were seen during the 1-year follow-up. The present case report emphasizes the pivotal role of repeat echocardiography in clinical decision-making and the life-saving potential of thrombolytic therapy without serious adverse effects.