The capacity to repair damaged DNA is a basic tool by which the mammalian cell maintains its genetic integrity and prevents neoplasm; however, DNA repair function could be modified by genetic polymorphisms. Recent molecular epidemiological studies have indicated that these genetic variants occur in the normal population and can be used to predict individual cancer risk. Since variation in the function of these genes might impact a cancer cell ’ s viability or resistance to treatment, genetic variants in DNA repair might act as a valuable marker in forecasting the results of cancer treatment. This possibility has been outlined by some clinical pilot studies of genetic polymorphisms in the DNA repair genes. With the biological importance of the DNA repair genes, studies of these genetic variants occurring in the general population will further our understanding of cancer etiology and behavior.