The Cys148Arg and Trp149Stop variants in the tumour suppressor gene ARLTS1 predispose to familial breast cancer, suggesting that these variants might also contribute to colorectal carcinogenesis. As the first to evaluate the association between Cys148Arg and Trp149Stop and colorectal cancer (CRC) risk, we genotyped 611 cases with CRC (including 77 cases with a first-degree family history) and 539 controls recruited from the German DACHS study. No significant differences in the genotype frequencies of Cys148Arg and Trp149Stop were observed between cases and controls. However, we showed a non-significant increased risk of familial CRC for both variants (OR=1.40 and 1.45), indicating a possible role of ARLTS1 in familial CRC.