High interindividual response variability was reported with capecitabine and oxaliplatin (CAPOX) regimen in colorectal cancer (CRC). The single nucleotide polymorphisms (SNPs) of the genes related to drug efflux transport (ABCB1) and DNA repair (ERCC) could result in altered tumour response. Hence, this study was designed to assess the influence of ABCB1, ERCC-1 and ERCC-2 gene polymorphisms on tumour response to CAPOX treatment in CRC patients of South Indian origin.