The mortality experience of an isolated Indian population in the Sioux Lookout Zone of northwestern Ontario from 1972 through 1981 is reviewed and compared with that of the Canadian population. Standardized mortality ratios for major categories of causes computed showed excessive risks in most conditions. Notable exceptions included circulatory diseases and neoplasms. Injuries and poisonings accounted for more than one-third of deaths. The proportionate mortality and age-specific mortality rates were considerably higher in all age groups in the Sioux Lookout Zone than in the whole of Canada. Excessive risks were found in almost all categories of accidental and violent deaths except motor vehicle accidents and accidental falls. Local conditions that contributed to the pattern observed are discussed. More than 90 percent of deaths from accidents and violence occurred before the medical care system was involved, highlighting the need for primary preventive strategies in reducing mortality due to these causes. While the infant mortality rate declined, pneumonia, gastroenteritis, and meningitis still accounted for 28 percent of infant deaths in the decade. Even with sudden infant death syndrome excluded, about 25 percent of infant deaths still occurred at home. Some features of the pattern of mortality reported here are also observed in other North American Indian groups undergoing the stresses of social change.