The cases of pulmonary thromboembolism (PTE) diagnosed in the clinical autopsies performed in our hospital during a 15-year period were reviewed. The incidence was 2.7% (63 cases). The most common disease associated with thromboembolism was cancer (41%). In 30 cases, thromboembolism involved more than 60% of the pulmonary circulation (group I), between 40% and 60% in 18 cases (group II), and less than 40% in 15 cases (group III). 30% of the embolisms were recurrent. A statistically significant correlation between the extension of the involved pulmonary circulation and the condition associated with thromboembolism was found. Whereas in patients with neoplasia the extension of pulmonary circulation involved by PTE was quite variable, the patients with cardiovascular disease or thrombophlebitis had PTE with invariably severe compromise of pulmonary vasculature (groups I and II).