Genome is consistently exposed to many factors leading to DNA damage. These damaging factors may be exogenous or endogenous. Living organisms possess DNA repair mechanisms in order to protect their genetic material from these injuries. Once a damage occurs, the cell responds to it with different metabolic pathways. Many experimental and epidemiological studies displayed clues about the casual relationship between DNA damage and repair systems, and cancer, aging and various genetic disease. DNA repair systems are essential biological mechanisms for the cell to survive and to maintain its genomic stability.