Intake of fish or omega-3 fatty acids may decrease risk of total and coronary heart disease death, but evidence from low-risk populations is less convincing. The authors assessed intake by using a food frequency questionnaire at baseline in a cohort of Iowa women aged 55-69 years. Among women initially free of heart disease and cancer (4,653 deaths over 442,965 person-years), there was an inverse age- and energy-adjusted association between total mortality and fish intake, with a relative risk of 0.82 (95% confidence interval: 0.74, 0.91) for the highest versus lowest quintile. Age- and energy-adjusted associations also were inverse (p for trend < 0.05), although not entirely monotonic, for cardiovascular, coronary heart disease, and cancer mortality. Adjustment for multiple other risk factors attenuated all associations to statistically nonsignificant levels. Estimated marine omega-3 fatty acid intake also was not associated with total or cause-specific mortality. In comparison, plant-derived alpha-linolenic acid was inversely associated with mortality after multivariable adjustment. Intake of neither fish nor marine omega-3 fatty acids was associated with breast cancer incidence. These findings do not argue against recommending fish as part of a healthy diet, as other evidence suggests benefit. Nevertheless, the authors of this 1986-2000 study could not verify that fish and marine omega-3 fatty acid intake had independent health benefits in these postmenopausal women.