Background <p>The increasing number of older adults and the burden of diseases in this age group have increased the need for health services, especially preventive services. The level of utilization of primary health services is a health challenge for older adults. This study aimed to investigate the experiences of older adults and primary health care providers regarding the factors affecting the utilization of these services.</p> Methods <p>The present descriptive-explanatory qualitative study examined physicians and urban and rural healthcare providers in Isfahan province from October 2024 to March 2025. A total of 56 participants were selected through purposive sampling for the study. In-depth and unstructured interviews were conducted to collect data. Sampling continued until no new ideas emerged during interviews, indicating that data saturation had been reached. The content analysis presented by Graneheim and Lundman was used to analyze the data. The present study employed four strength criteria: credibility, confirmability, transferability, and dependability.</p> Results <p>Five themes emerged from 210 open codes. These codes were grouped into five interrelated themes: Personal determinants of healthcare utilization; structural and environmental determinants of access; policy and system-level determinants of service utilization; interpersonal communication and clinical conduct; and operational capacity and system performance. These themes together describe how older adults’ healthcare services are experienced, delivered, and utilized in comprehensive health centers.</p> Conclusion <p>According to the results, the provision of primary healthcare services for older adults has personal, interpersonal communication, structural, environmental, policy, and health system problems. In this regard, policymakers must review and improve primary health service programs for older adults.</p>