The increase in the therapeutic arsenal in the last 20 years, has given rise to changes in treating colorectal cancer (CRC) with only pyrimidines to combine several cytotoxic drugs. However, the present question is to determine the optimal sequence of this combination. This review presents an update of data on chemical and clinical features of chemotherapy used for colorectal cancer and the mechanisms of cellular resistance and potential predictive and prognostic biomarkers, which may contribute to a better selection of a therapeutic strategy.