A 52-year-old previously healthy man experienced acute severe dyspnoea after suffering from gastroenteritis for 3 days. After arrival of the ambulance, cardiac arrest with an initial rhythm of electro mechanical dissociation occurred. Circulation was restored after 10 min of cardiopulmonary resuscitation but soon cardiac arrest reoccurred. Based on a strong clinical suspicion of massive pulmonary embolism, thrombolytic treatment with heparin 5000 IU and reteplase 20 U, given as single boluses and heparin was continued as an infusion 1000 IU h(-1). After 7 min of continued resuscitation, circulation was restored and after 40 min the vital functions began to stabilize, thus indicating pulmonary reperfusion. The diagnosis of pulmonary embolism was confirmed by a ventilation-perfusion scan and by spiral computerised tomography. The patient was discharged from intensive care after 2 days with a cerebral performance category I. Based on previous calculations, the annual number of patients who present with massive pulmonary embolism leading to cardiac arrest (and thus who would theoretically be candidates for thrombolytic treatment) was estimated to be 0.7/100000 inhabitants in this emergency medical services system.