Pulmonary thromboembolism has an incidence of more than 69/100 000 population but may be underdiagnosed because of the non-specific character of its symptoms and difficult differential diagnosis. The prognosis is worse if the pulmonary thromboembolism is massive and associated with haemodynamic instability, whereupon mortality rises to over 50%. Cardiogenic shock supervenes and cardiopulmonary arrest is often inevitable. This emergency can only be prevented by aggressive therapy with thrombolytic agents. The case history is described of a 25-year-old woman in cardiogenic shock leading to prehospital cardiac arrest in which intravenous access was impossible. Resuscitation drugs were given by the intraosseous route and, with a suspected diagnosis of massive pulmonary thromboembolism, it was decided to start thrombolysis by the same route before transport to hospital. The treatment was a complete success, and the patient was discharged from hospital with no sequelae after 39 days.