Colorectal cancer (CRC) is a major health burden worldwide and is the second-leading cause of cancer-related death in Europe. CRC is a complex disease resulting from a series of genetic and epigenetic changes that lead to a stepwise progression from normal mucosa to dysplasia and finally to carcinoma. In this study, we present genetic association results between 25 tag single-nucleotide polymorphisms and CRC in a case–control study (203 cases, 296 controls) of a Han Chinese population. We found that rs1143634 in the interleukin-1β (IL1B) gene and rs1800871 in the interleukin-10 (IL10) gene were associated with increased risk for CRC in the Han Chinese. Further haplotype analysis revealed that the ‘GAC’ in the SMAD7 (mothers against decapentaplegic homolog 7) gene was found to increase CRC risk (odds ratio=1.48; 95% confidence interval, 1.09–2.01; P=0.012). Our results, combined with previous studies, suggest that IL10, PSCA, IL1B, and SMAD7 are significantly correlated with CRC susceptibility in the Han Chinese population.