Abstract: Individualized treatment based on molecular characteristics of colorectal cancer patients can help doctors achieving the best therapeutic effect and the slightest adverse reaction. For advanced colorectal cancer patients, RAS gene status including KRAS and NRAS should be determined before anti-EGFR targeted therapy; determining UGT1A1 gene polymorphism is suggested if administering irinotecan-based regimen; however, the predicting value of other molecular characteristics, such as BRAF mutations, PIK3CA mutations, mRNA expression of ERCC1, etc., is still unclear. This article reviews the related genes associated with therapeutic efficacy or toxicity of colorectal cancer, and gives advice about clinical decisions.