Objectives: Cognitive declines that inevitably come with aging make it difficult for elderly to understand health information and take appropriate actions to treat diseases and manage their health. The goal of this research was to improve health literacy of the elderly, especially those with low education, by designing a health message to accommodate changes due to cognitive declines of the elderly. Methods: A 2×2 experiment examined the effect of message types (i.e., original versus new design message) and educational level (low versus high education). Participants who were at least 65 years old and healthy participated in the study. Results: The new message design resulted in higher comprehension score and faster reading time. The effect of the design was greater with low education group. Less problems were reported with respect to the new design as compared to the original design. Conclusions: The results suggest that we can improve the health literacy of the elderly, especially those with low education, by applying design principles that take into account of the cognitive changes that come with aging. More active application of these design principles will help elderly population to better manage and prevent health problems.