Although nutrients or agents with antioxidant properties were reported to show a preventive effect on cognitive decline in animal studies, epidemiologic data on select antioxidants have shown conflicting results. We investigated whether a combination of antioxidants from supplements is effective for the improvement of cognitive function of elderly. Forty-one subjects from a community dwelling aged 65 years and older took supplements containing n-3 polyunsaturated fatty acids (n-3 PUFA), lycopene, and Ginkgo biloba extracts (GE) daily for 3 years. The data of 622 subjects without supplement intake were used as control. We investigated the changes in cognitive function during a 3-year follow-up. We also investigated the influence of apolipoprotein E (APOE) genotype on the effect of antioxidants. We found that a combination of antioxidants improved cognitive function of aged persons after 3 years. Our present study also indicated this improvement in cognitive function with supplement intake in both APOE4 non-carrier (E4-) and APOE4 carrier (E4+) groups. Especially, in E4+, we found a large effect size of the improvement of cognition. When multiple antioxidants are used in combination, they protect against vulnerability to other agents and synergistically potentiate their antioxidant properties. These synergistically potentiated antioxidant effects of agents contribute to the improvement of cognitive function.