Objective: Biological and psychological factors contribute to coronary artery disease (CAD). The purpose of this study was to investigate the relationship between spiritual well-being and CAD severity and determine the mediating effects of anger rumination and worry on this relationship. Design: Descriptive, cross-sectional survey. Setting: Afshar Hospital in Yazd, Iran. Method: Participants were 327 patients with CAD (138 women, 189 men). Spiritual well-being, anger rumination, worry and CAD severity were measured using demographic and medical information questionnaires, the Spiritual Well-Being Scale, the Anger Rumination Scale, the Penn State Worry Questionnaire and Gensini method. Mediation analysis was conducted using the PROCESS macro. Results: CAD severity was negatively correlated with spiritual well-being (r=-0.62, p<0.01) and positively correlated with anger rumination (r=0.58, p<0.01) and worry (r=0.33, p<0.01). The relationship between spiritual well-being and CAD severity was mediated by anger rumination. The direct effect of spiritual wellbeing on CAD severity was statistically significant ([beta]=-0.06, 95% confidence interval [CI] [-0.09, -0.04]). We find a significant indirect effect of spiritual well-being on CAD severity through anger rumination ([beta]=-0.03, 95% CI [-0.05, -0.02]). Conclusion: These results highlight the potential benefits of spiritual well-being for patients with CAD to help them reduce anger rumination and, consequently, CAD severity.