Two cases of severe pulmonary embolism associated with right atrial thrombosis are reported. In the first case, fibrinolytic therapy was administered and was thought to be a causative factor in the death of the patient due to massive pulmonary embolism. In the second case, the patient was referred for surgery and two enormous thrombi were extracted. Unfortunately, the outcome was fatal. These two cases were confronted with the results of the literature. They strongly suggest that echocardiography should be a first-line investigation in severe pulmonary embolism. The detection of right atrial thrombosis modifies the clinical strategy and orientates treatment towards surgical referral when the patient's condition allows it.