Having a healthy lifestyle is a prerequisite for achieving sustainable development. Moreover, social capital is one of the important variables affecting the health of individuals in society. Thus, the purpose of this study was to investigate the relationship between social capital and health-related quality of life among rural people in Dena region located in southwest of Iran. 300 households were selected using multistage cluster sampling method. For data collection, SF-36 standard questionnaire was used to measure health-related quality of life. A research made questionnaire was also applied in order to examine social capital which its validity and reliability were confirmed. The correlation coefficients between both physical health and mental health and 5 dimensions of social capital was positive. Furthermore, the correlation between mental health and social trust and social networks was significant; moreover, the correlation coefficient between mental health and social cohesion was significant. However, the correlation between mental health and social norm and social participation was not significant. Considering a relationship between mental health and social trust as well as social networks and social cohesion, enhancement of the above dimensions should be taken into account in order to improve mental health.