Objective - To understand the role and influence of villagers' trust for the health insurer on enrollment in a community-based health insurance (CBHI) scheme in Cambodia. Methodology/approach - This study was conducted in northwest Cambodia where a CBHI scheme operates with the highest enrollment rates in the country. A mixed method approach was employed to gauge how individuals in the community trust the health insurer, and whether this plays a role in their decisions to enroll in CBHI schemes. Focus groups and household surveys were carried out to identify and measure trust levels, and to explore the association between insurer trust and enrollment in CBHI schemes. Findings - Although villagers generally trusted the health insurance organization, villagers with poor experiences with other organizations in the past were less willing to trust the insurer. Insurer trust represented a combination of interpersonal and impersonal trust. After controlling for demographic factors, health care utilization, and household socioeconomic status, insurer trust levels for villagers who newly enrolled (RRR = 1.07, p<0.001) and renewed insurance (RRR = 1.15, p<0.001) were significantly higher than those who never enrolled in CBHI schemes. Implications for policy - This study illustrates the relationship between CBHI enrollment and villagers' trust for the health insurer in a lowincome, post-conflict country. It highlights the need for staff of health insurance organizations to place greater emphasis on building trusting interpersonal relationships with villagers. Understanding the nature of trust for the health insurer is essential to improve health insurance enrollment and protect people in poor rural communities against the impact of health-related shocks.