Molecular analysis and blast colony assay were performed on patients with Philadelphia chromosome-positive acute leukemia (Ph+ AL). All patients were diagnosed as ALL- L2 and 3 were My+ ALL. Nine of the 12 cases had rearranged immunoglobulin heavy chain, and 4 had rearranged TCR beta. TCR gamma rearrangement was noted in 3 patients, and TCR delta involvement was also noted in 6 patients. Clonal culture analysis revealed that leukemia cells of M-BCR rearranged Ph+ AL cases had a potential to proliferate by myelopoietic CSFs and ILs, however, M-BCR nonrearranged Ph+ AL did not. These results indicate biological and immunogenotypic heterogeneity of Ph+ AL.