Sirtuins, a family of NAD(+)-dependent deacetylases, help organisms to respond to metabolic and genotoxic stress through diverse pathways, including metabolic homeostasis, cell survival pathways and cell-cycle control. Evidence accumulated over the past decade, including recent descriptions of mouse knockout models for each of the seven mammalian Sirtuins, suggests that protection of genome stability is among the most important roles of Sirtuins during stress response. Our current knowledge suggests that Sirtuins promote genome integrity through a variety of mechanisms, the majority of which involve a direct role in chromatin-related functions. Here, we review these mechanisms and discuss their implications for cell physiology and tumorigenesis.