A 79[correction of seventy]-year-old patient, who has been in bed a long time, suffered an episode of sudden dyspnea, tachycardia and tachypnea. An electrocardiogram registered at her admission in the coronary care unit showed a normal rhythm with right axis deviation and S1Q3T3 pattern and ST segment alterations. A ventilation-perfusion lung scanning demonstrated segmental perfusion defects with high probability of pulmonary embolism. She developed a low cardiac output syndrome, which neither responded to the volume expansion nor to the inotropic drugs. The bed-side hemodynamic measurements were a systolic pulmonary pressure of 60 mmHg, with a diastolic pressure of 18 mmHg and capillary wedge pressure of 13 mmHg with high pulmonary resistance. With this evidences, the diagnoses of massive pulmonary embolism was done, thrombolytic treatment was decided on. Two hundred and fifty thousands international units of streptokinase was administered, and then 100.000 UI/hour in 24 hours; after that with intravenous heparin. The low cardiac output syndrome disappeared. The patients recovered her systemic arterial pressure and her diuresis. The electrocardiographic signs vanished and both the pulmonary pressure and resistance decreased. We discussed the importance of intravenous thrombolytic treatment in massive pulmonary embolism. We concluded than this treatment is an useful strategy that not always needs a pulmonary arteriography, and could be used in low complexity centres, successfully in the massive pulmonary thromboembolism with severe hemodynamic damage.