To determine the accuracy of the antemortem diagnosis of major pulmonary embolism, we reviewed 1276 autopsy reports at St Michael's Hospital, Toronto, from 1980 to 1984. Of 44 patients identified with major pulmonary embolism as the cause of death or a major factor contributing to it, 14 (31.8%) had the diagnosis suspected before death. We could not find any distinctive features separating these patients from those in whom the diagnosis of pulmonary embolism was not suspected before death. We conclude that major pulmonary embolism is still underdiagnosed in hospitalized patients, despite the availability of lung scanning and pulmonary angiography.