Fanconi anemia (FA) is a rare, autosomal recessive disease characterized by multiple congenital abnormalities, bone marrow failure, and cancer susceptibility. Although traditionally described as a classic clinical syndrome, as more is discovered regarding its basic molecular and cell biology, FA is emerging as a true premalignant syndrome. Two of the genes of the five known complementation groups have been cloned, and work to understand their function is underway. Further understanding of these gene products has lent new ideas concerning modes of novel therapy, including gene therapy. The impact of molecular biology on our understanding of basic biology and the clinical care of FA patients is discussed.