Causes of death in the year 1970 were analyzed retrospectively on the basis of clinical and pathologic reports of 506 cases in the Roswell Park Memorial Institute and Hospital. The single major cause of death was infection (36%), which was also a contributory factor in an additional 68% of the cases. Other important causes of death were hemorrhagic and thromboembolic phenomena (18%), which also were contributory factors in an additional 43%. Organ invasion by neoplastic cells including hepatic failure was the major cause of death in 10% and was a contributory factor in 5%. Cachexia was reported as major cause of death in 1% and as contributory factor in 0.4%. Respiratory failure due to various causes (including aspiration) was the main mechanism of death in 19% and a contributory factor in 3%. Cardiovascular insufficiency was the major cause of death in 7% and a contributory factor in 3%.