BACKGROUND AND AIM. The existing tests practiced on a large scale in colorectal cancer (CRC) screening do not fully accomplish the goal of best specificity and sensitivity or either an optimal cost/efficiency ratio. We aimed to analyze genetic mutations diagnosed in the DNA of exfoliated cells in the stool of the patients diagnosed with CRC through screening. We also aimed to demonstrate the similarity between the detected mutations in tumor samples and in exfoliated cells in the stool in order to prove the reliability of these cytogenetic tests, so that they could be introduced in CRC screening program. METHODS. We studied 200 patients diagnosed with CRC from whom we prelevated biopsy and stool samples. Samples were submitted to genetic analysis through denaturing gradient polyacrylamide gel electrophoresis method, and through polyacrylamide gel electrophoresis method for the heteroduplex analysis. Analyzed genes were APC, COL11A1, MLH1, MSH2 and MSH6. The chromosomal study was carried out using the PRINS technique. RESULTS. We discovered mutations in the APC gene (exons 4, 9, 13, and 15c) and COL11A1 gene (exon 54). Our chromosomal study detected instability of chromosomes 1, 7, 9, 20, and in 10 achrocentric chromosomes. CONCLUSIONS. Our results plead for the implementation of proposed cytogenetic tests in CRC screening programs.