Of 13,913 patients examined at autopsy between 1939 and 1980, the diagnosis of nonbacterial thrombotic endocarditis (NBTE) was made in 99 instances. There were 53 males and 46 females ranging in age from 4 to 89 years. Vegetations were found on the aortic valve in 39; the mitral in 37; the tricuspid in nine; and the pulmonic in two. Two-valve involvement was present in 12 cases. Malignant neoplasms were found in 42 autopsies. Embolism to the brain was found in 33 cases and to other organs in 62. Coagulation abnormalities were documented in 22 cases, and a distinct picture of disseminated intravascular coagulation was found in ten cases. The presence of thrombophlebitis elsewhere in the body should arouse suspicion of NBTE. The high incidence of multiple emboli and its association with malignant neoplasms and with a variety of cardiovascular, pulmonary, renal, and gastrointestinal disorders should provide clues for recognition of this serious disorder. © 1982 American Medical Association All rights reserved.