We studied the frequency and characteristics of death due to pulmonary embolism among all hospital and surgical patients in a university hospital from 1966 through 1980. Of 6,858 deaths, 3,412 autopsies were performed using a standardized and sensitive technique for pulmonary dissection. Our study showed that 6% of deceased patients (4.7% of surgical patients) had massive fatal embolism. Significant declines in embolism mortality were noted during this time period for hospital and surgical patients. The percentage of embolism cases among autopsies fell from 9.3% in the first five years to 3.8% in the last five years. Excluding patients receiving anticoagulants at the time of death, these percentages fell from 8.8% to 2.7%. The estimated hospital mortality rate for embolism fell during the same years from 0.37% of hospital discharges to 0.13%. During the years studied, the use of anticoagulants among all adult patients at the hospital increased from 4% of patients to nearly 12.3%. This and other evidence suggest the possibility that both the incidence rate and the case-fatality rate for pulmonary embolism have decreased in the hospital population we studied.