The area of mammalian DNA repair and its relationship to cancer and therapeutic approaches is rapidly growing, both through the studies of basic mechanisms and in the use of this knowledge for translational applications. We have attempted to briefly and succinctly cover the four pathways of mammalian DNA repair, which are: direct reversal, mismatch, nucleotide excision, and base excision repair. We have also tried to identify and reference results in the literature relating the various repair pathways to cellular resistance following chemotherapeutic treatments and to provide some potential direction whereby laboratory results may be applicable to clinical therapeutics, particularly for cancer treatments.