Background: It was suggested that dietary patterns might play a role in the pathogenesis of nephrolithiasis. The aim of this study was to determine the relationship between dietary patterns and the occurrence of calcium oxalate kidney stone disease. Methods: A case-control study was conducted on 634 male and female participants aged 18-65 in Tehran using a convenient sampling method. The participants were investigated in the case (n = 317) and control (n = 317) groups. Demographic and anthropometric information, medical history, physical activity, and dietary intake were collected by interview. A validated 147-item food frequency questionnaire was administered to assess the dietary patterns. Factor analysis was also applied with principal component approach (PCA) to determine the major dietary patterns. Results: The findings showed two major dietary patterns using 41 food groups. Significant differences were observed in nutritional factors and physical activity between the case and the control groups. After adjusting the covariates, the risk of calcium oxalate kidney stone was significantly higher for those in the highest tertile of unhealthy dietary pattern compared to the lowest ones (OR, 3.83; 95%CI, 2.22-6.61). Additionally, no relationship was found between the healthy dietary pattern and the risk of calcium oxalate kidney stone in any of the four logistic regression models
(P for trend > 0.05) (OR,0.95; 95%CI, 0.58-1.55). Conclusion: We found that the unhealthy dietary pattern was strongly associated with increased risk for calcium oxalate kidney stones.