In a retrospective study of 210 patients with pulmonary embolism diagnosed by ventilation perfusion lung scan or at post-mortem, the incidence of pulmonary embolism was greater in patients over 50 years old (1.4%; P less than 0.05). This was largely due to an increased prevalence of serious associated disease (53%; P less than 0.05). Mortality in elderly patients (70 years and older) diagnosed by ventilation perfusion lung scan was similar to that in younger age groups (P greater than 0.05). However, the number of cases first diagnosed at post-mortem (44.50%; P less than 0.05) and total mortality (55%; P less than 0.05) were highest in this age group. Of elderly patients first diagnosed at post-mortem 14 (32%; P less than 0.05) had no other associated disease and had a recorded duration of symptoms sufficient to have allowed premortem diagnosis.