The recurrent translocation t(11;16)(q23;p13) has been reported to be associated with therapy-related acute leukemia. The MLL gene involved in other 11q23 abnormalities was also rearranged by this translocation. We analyzed two patients with myelodysplastic syndrome with t(11;16) and showed that the MLL gene on 11q23 was fused with CREB-binding protein (CBP) gene on 16p13 in these patients. The CBP gene encodes a transcriptional adaptor/coactivator protein and it is mutated in patients with Rubinstein-Taybi syndrome. The CBP gene is also involved in acute myeloid leukemia (AML) with t(8;16)(p11;p13). In-frame MLL-CBP fusion transcripts combine the MLL AT-hook motifs and DNA methyltransferase homology region with a largely intact CBP. Our results combined with the finding of the MOZ-CBP fusion in t(8;16)-AML suggest that the CBP gene may be associated with leukemogenesis through translocations.