Social capital is a multi-faceted phenomenon in social sciences that massively affects many social fields. It can be a helpful factor in promoting health. Among the groups with high burnout, nurses have always shown higher levels of burnout. Studies have revealed that social capital can be an important factor affecting burnout. This study aimed to determine the extent of the effect of social capital on burnout in nurses of a trauma referral teaching hospital in Rasht. This was a descriptive correlational study conducted on 214 nurses of a trauma referral teaching hospital. Maslach standard questionnaire and the social capital questionnaire devised by Boyas and colleagues were used. Data were analyzed using descriptive statistics, Pearson correlation coefficient, and linear regression analysis to determine the extent of the effect of social capital on burnout. The study showed an inverse association between social capital and burnout. The intensity of the relationship was -0.451 (P<0.0001). Also, the linear regression model of social capital on burnout variable showed that the regression coefficient of social capital equaled -0.34. The determination coefficient of this regression model indicated that social capital explained 20% of burnout changes. The results showed high burnout in emotional exhaustion dimension and an inverse association between social capital and burnout. Thus, attempts should be made to promote social capital dimensions among nurses. Given the inevitability of job stress in a nursing environment, and managers should plan on improving the working conditions and training techniques to deal with such stress.