PurposeThis study contributes to the understanding of primary care bypassing in China by focusing on an underexplored demographic: the oldest old (individuals aged 80 years and above). While previous research has predominantly focused on health system determinants of bypassing, this study also considers social and cultural factors involved in the oldest old's health-related decision-making and health-seeking behaviour.MethodsData were collected through 20 in-depth interviews with participants from Shandong, Henan, and Shanghai. Data analysis combined inductive and deductive approaches. Initially, we used the constructive grounded theory approach of inductive coding to allow codes to emerge from participants' narratives. Later, we integrated the emerging categories within the Health Belief Model to provide a more structured understanding of the factors influencing bypassing behaviours.ResultsOur findings reveal that bypassing cannot be explained only through distrust in the quality of services and resource shortages at primary care facilities. Participants often regarded ageing as a natural, inevitable process, which, combined with the cultural norm of endurance, delayed care-seeking for minor health issues and reduced the use of preventive services. Family involvement in health-related decisions also contributes to bypassing, as children often push for hospital-based care, reflecting both the cultural expectation of filial devotion and the belief that hospitals provide better care. Personal connections within hospitals increase trust, facilitate access, and secure privileges, which reduce the appeal of primary healthcare facilities.DiscussionOur findings suggest that health system improvements alone, albeit necessary, are insufficient to reduce the bypassing of primary care. Interventions should also address the socio-cultural factors influencing this practice. Specifically, this paper calls for improving the quality of primary health services, reforming the essential medicines policy, and promoting cultural change by prioritizing preventive care and improving the general perception of community health centres, township health centres, and village clinics.