Colorectal cancer is one of the most common cancers worldwide and among the Croatian population. To improve colorectal carcinoma prevention, contribute to its early detection and improve the outcome of treatment, it is necessary to find reliable prognostic and predictive factors as well as risk factors. Investigations of the ABO blood group correlation with gastrointestinal carcinoma show the association of non-O blood groups with an increased risk of disease. Such investigations in the case of colorectal cancer are few and show contradictory results. The aim of this study was to examine the association between the ABO genotypes and the risk of colorectal cancer in the Croatian population. The study included 80 patients with colorectal carcinoma and a control group of 303 healthy volunteer blood donors. Using the PCR-SSP method, genotyping was performed on 5 main alleles (O1, O2, A1, A2, B) and 15 ABO genotypes. The results were statistically tested by odds ratio, Chi-square test and an analysis of the proportional difference. No apparent statistically significant difference between ABO genotypes was obtained by odds ratio testing. The results of the same test at the phenotypic level showed 1.79 times the increased risk for colorectal carcinoma of blood type A compared to blood group O (OR=1.79; 95% CI=1.01–3.19). The proportional difference test showed that the incidence of allele O1 was statistically significantly higher in the control group (0.62) compared to the group of patients (0.53). Borderline statistical significance was obtained according to the presence of allele A2 which was statistically lower in the control group (0.035) compared to the group of patients (0.069). The results of this study confirmed the previous major findings due to gastrointestinal carcinoma and association with the ABO blood groups, and represent a good basis for genetic and in silico research of the mechanisms by which the ABO blood groups antigens contribute to carcinogenesis.