This report examines the relationship of dietary fat and dietary cholesterol to mortality during a 10-year surveillance of a cohort of men of Japanese descent residing in Hawaii. The consumption of dietary fat (measured in grams) is related inversely and significantly to total mortality. No significant relationships exist between grams of dietary fat and any of the specific causes of death examined. No significant relationships are found between dietary saturated fatty acids (SFA, measured in grams) or dietary cholesterol (measured in milligrams) and any of the specific causes of death examined. In contrast, percentage of calories as fat is related inversely not only to total mortality, but to cancer mortality and to stroke mortality; and it is related directly to coronary heart disease (CHD) mortality. Percentage of calories as SFA is related inversely to cancer mortality and to stroke mortality, and it is related directly to CHD mortality. Only the relationship to stroke mortality remains significant in multivariate analysis if calories from alcohol are excluded from the computation. Dietary cholesterol per 1000 calories is related directly to CHD mortality. While these data provide support for the diet-heart hypothesis, they also suggest that men with low fat intakes have a higher total mortality rate than men with higher fat intakes. This increased risk, due to an excess risk of death from stroke and cancer, indicates that there is no overall beneficial effect from a low fat diet in this cohort.