Chromosome translocations are closely associated with a particular morphologic or phenotypic subtype of acute myeloid leukemia (AML). Cloning the genes at the breakpoints of these rearrangements has had a major impact on our understanding of the molecular biology of AML. Thus, cytogenetic or direct molecular genetic methods have become an essential part of the routine diagnostic evaluation and follow-up of AML patients. This review describes the MLL gene on 11q23 including three types of t(10;11), the TLS/FUS gene on 21q22, the AML1 gene on 21q22, and the NUP98 gene on 11p15. The target gene(s) of MLL is unknown at present, but it appears to be involved in maintaining function of some of the homeobox genes. The transcriptional coactivators, CBP and p300, were found to be involved in leukemogenesis through translocations. Characterization of the functions of genes involved in these translocations has enriched our understanding of their roles in leukemogenesis, and provided some suggestions for new therapy.