Syncope is a common cause of hospitalization, and its frequency increases with age. Its prognosis is largely unpredictable, pending the origin of the sudden loss of consciousness. We report a case of an old woman affected by severe chronic heart failure, who died soon after the development of an episode of syncope, which was eventually attributed to pulmonary embolism. Anticoagulant therapy, promptly instituted, was ineffective. In the differential diagnoses of syncope, pulmonary embolism should always be considered, especially in old patients with risk factors for venous thromboembolism such as a severe heart failure. In patients with high risk of death according to the widely adopted risk stratifications score, aggressive therapy may be considered also in elderly people to prevent unfavourable outcomes.