Background and Objectives: Inflammatory bowel disease (IBD) consists of two main types, Crohn's disease (CD) and ulcerative colitis (UC). The characteristics of IBD patients have not been studied widely in Iran; hence we aimed to survey the epidemiology of this disease in the Iranian population. Methods: This study was conducted based on the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) guideline. Joanna Briggs Institute (JBI) Critical Appraisal Checklist was admired for the quality assessment of the included studies. For assessing heterogeneity, we used the Cochran test and I2 statistics. Meta-regression analysis was performed for mean age of CD and UC with conduction year of studies. Results: Based on the results of this study, the male/female ratio for IBD, CD, and UC was 1.16 (95% CI: 1.05-1.26), 0.98 (95% CI: 80-1.16), and 1.14(95% CI: 1.04-1.23), respectively. The prevalence of smoking in IBD, CD, and UC was 7.6% (95% CI: 3.9%– 14.3%), 9.9 %( 95% CI: 7.7%– 12.8%), and 9.6% (95% CI: 4.5%– 19.3%), respectively. The mean age of the IBD, CD and UC population was 36.28 (95% CI: 34.59-37.97), 35.70 (95%CI: 31.76-39.64), and 37.21 (95% CI: 34.44-39.99) years old, respectively. The results of the meta-regression analysis showed that the average age of UC and CD patients has decreased in recent years. Conclusions: In conclusion, we found that cigarette smoking consumption was significantly higher in CD patients. CD patients were younger compared to UC patients. In addition, the age of UC and CD patients has decreased in recent years