Twenty-six white male subjects, who worked with plutonium (239Pu) during World War II at Los Alamos, have been given medical examinations periodically over a period of 42 y to identify potential health effects. Inhalation was the primary mode of Pu exposures. The latest examinations, including urine bioassay and in-vivo measurements for radioactivity, were performed in late 1986 and 1987. The average age of the 22 living subjects in 1986 was 66 y. The diseases and physical changes noted in these persons are characteristic of a male population in their 60s. Estimates of individual Pu depositions, including lung burdens, as of 1987 or at time of death range from 52 to 3180 Bq (1.4 to 86 nCi) with a median value of 500 Bq (13.5 nCi). Four persons from the original group had died as of 1987. The causes of death were lung cancer, myocardial infarction, accidental injury, and respiratory failure due to pneumonia/congestive heart failure. Expected deaths based on U.S. death rates of white males, adjusted for age and calendar year, are 9.2 based on U.S. rates (standardized mortality ratio = 0.41). Subsequent to 1987, three additional deaths occurred from atherosclerotic heart disease, lung cancer, and osteogenic sarcoma. The bone sarcoma case is discussed in terms of Pu exposure, the natural incidence of this disease, anatomical location of the tumor, and bone tumors observed in Pu-exposed dogs. Plutonium deposition in this man is estimated to have been below current radiation protection guidelines.