Fanconi anaemia (FA) is a disease characterized by progressive bone marrow failure, developmental defects, and cancer predisposition. Hypersensitivity to DNA cross-linking agents such as mitomycin C (MMC) is a characteristic feature of FA cells. Somatic cell hybridization studies have revealed that FA is genetically heterogeneous, comprising at least eleven complementation groups. Nine FA genes have been identified so far: FANCA, FANCB, FANCC, FANCD1/BRCA2, FANCD2, FANCE, FANCF, FANCG and FANCL. The FA proteins are members of a multi-component pathway that functions to maintain genomic integrity, in which an important role has been assigned to FANCD2, whose activation is one of the key events in the DNA damage response induced by MMC or ionizing irradiation.