Background:Health literacy is a measure of an individual's ability to read, comprehend, and act on medical instructions. Limited health literacy can reduce the adults’ ability to comprehend and use basic health-related materials, such as prescription, food labels, health education pamphlets, articles, appointment slips, and health insurance plans, which can affect their ability to take appropriate and timely health care action. Nowadays, low health literacy is considered a worldwide health threat. So, the purpose of this study was to assess health literacy level in older adults and to investigate the relationships between health literacy and health status, health care utilization, and health preventive behaviors.Materials and Methods:A cross-sectional survey of 354 older adults was conducted in Isfahan. The method of sampling was clustering. Health literacy was measured using the Test of Functional Health Literacy in Adults (TOFHLA). Data were collected using home interviewing. Health status was measured based on self-rated general health. Health care utilization was measured based on self-reported outpatient clinic visits, emergency room visits, and hospitalizations, and health preventive behaviors were measured based on self-reported preventive health services use.Results:Approximately 79.6% of adults were found to have inadequate health literacy. They tended to be older, had fewer years of schooling, lower household income, and were females. Inadequate health literacy was associated with poorer general health (P < 0.001). Health literacy level was negatively associated with outpatient visits (P = 0.003) and hospitalization (P = 0.01). No significant association was found between health literacy level and emergency room utilization. Self-reported lack of PSA (Prostate-Specific Antigen) test (P < 0.001) and fecal occult blood test (FOBT; P = 0.003) was higher among individuals with inadequate health literacy than those with adequate health literacy. No significant association was found between health literacy level and mammogram in the last 2 years.Conclusion:Low health literacy is more prevalent in older adults. It indicates the importance of health literacy issue in health promotion. So, with simple educational materials and effective interventions for low health literacy group, we can improve health promotion in the society and mitigate the adverse health effects of low health literacy.