Cellular DNA is constantly bombarded with environmental and chemical assaults that damage its molecular structure. In addition, the normal process of DNA replication is prone to error and may introduce mutations that can be passed to daughter cells. If left unrepaired, these DNA lesions can have serious consequences, such as cancer.Written and edited by experts in the field, this collection from Cold Spring Harbor Perspectives in Biology reviews the mechanisms that cells use to recognize and repair various types of DNA damage. Contributors discuss base excision repair, nucleotide excision repair, mismatch repair, homologous recombination, nonhomologous end joining, the SOS response, and other pathways in prokaryotes and eukaryotes, and describe how these processes are linked to DNA replication, transcription, and cell cycle controls. The repair of telomeric and mitochondrial DNA is described, as is the influence of chromatin structure on DNA repair. This volume also includes discussion of human genetic diseases that involve defects in DNA damage repair. It is an essential reference for molecular and cell biologists, medical geneticists, cancer biologists, and all who want to understand how cells maintain genomic integrity.