In the treatment of tumor patients, how to select the chemotherapy regimen with better efifcacy, less toxicity and expense is a difficult problem that perplexes clinical doctors for a long time. Pharmacogenetics is to study the influence of genetic factors on pharmacokinetics, whereas pharmacogenomics is to study the relationship between various gene mutations and drug efifcacy and safety. With molecular biology developing, pharmacogenetics and pharmacogenomics are considered to be essential in the reduction of adverse reactions, improvement of efficacy and realization of individualized treatment. In this article, the clinical application and evaluation of pharmacogenomics in tumor chemotherapy were primarily investigated.