Abstract Colorectal cancer (CRC) has one of the highest mortality due to the late diagnosis and a lack of proper predictive and prognostic markers. According to the current knowledge, DNA repair processes are involved both in the onset of CRC and in the treatment efficacy. In the present study, we analyzed the link between functional genetic polymorphisms (SNPs) in DNA repair genes covering the main DNA repair pathways (relevant for therapy response) in relation with the risk of CRC and clinical outcomes. Our set of candidate polymorphisms was selected according to different functional and genomic databases (FSNP, GAD, Linkage Disequilibrium, Gerp++, SiPhy). FSNP database provides integrated information about the functional effects of SNPs which are predicted and indicated at several levels (protein coding, splicing regulation, transcriptional regulation, post translation). We have focused on those affecting protein coding. We hypothesize that these modified proteins modulate the function/efficiency of DNA repair, and thus may have an effect on CRC. Sixteen polymorphisms in twelve DNA repair genes (C19orf40, EME1, FANCI, MUS81, NEIL3, POLE, POLN, POLQ, RAD51D, REV1, REV3L, RPA1) were analyzed in DNA samples of 1080 cases and 1442 controls from the Czech Republic. Clinical data at diagnosis and complete information on follow up were provided for all patients. Genetic variations in several DNA repair genes were associated with clinical outcome. In particular, CRC patients carrying the AG heterozygous genotype for rs5030755 in RPA1 gene displayed a longer survival and decreased recurrence risk (Overall Survival (OS): HR 0.74; 95% CI 0.56-0.98; p = 0.04 and Event-Free Survival (EFS): HR 0.72; 95% CI 0.54-0.95; p = 0.02). This association with better OS was more pronounced in individuals with colon and sigmoideum cancer (HR 0.58; 95% CI 0.4-0.83; p = 0.0035). Understanding the SNPs effect on the treatment response, resulting ultimately into low-cost and low-invasive markers, is regarded as very important for the possibility to tailor patient specific treatment strategy. Individualized therapy will eventually help to improve therapeutic efficacy and to minimize toxicities. The present results identified plausible candidate DNA repair gene variants potentially affecting clinical outcome in relation to CRC patient's survival. Supported by grant GA UK 112515, GA CR 15-14789S Citation Format: Katerina Jiraskova, Jana Slyskova, Fabio Rosa, Cornelia Di Gaetano, Barbara Pardini, Veronika Vymetalkova, Pavel Vodicka. Nonsynonymous functional variants in DNA repair genes in sporadic colorectal cancer: searching for predictive and prognostic markers. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3409.