Abstract: Objective To study the application of dual color-dual fusion fluorescence in situ hybridization（DC-DF-FISH） in detection of gene rearrangement in adult acute leukemia（AL） patients. Methods AML1/ETO,MLL,PML/RARa,BCR/ABL gene rearrangement was detected by DC-DF-FISH in 26 adult AL patients and compared with that detected by routine R-band. Results Four marker chromosomes were detected in 26 adult AL patients with a positive rate of 15.4%.No abnormal chromosome containing 11q23 was found in 17 patients with normal or abnormal karyotypes.Positive specific marker genes were detected in 8 patients by DC-DF-FISH and R-band respectively,with a positive rate of 30.8%. Conclusion DC-DF-FISH can reliably detect the PML/RARa,MLL,and AML1/ETO gene rearrangement,and can thus be used in diagnosis of AL,in judgment of therapeutic effect,and in detection of small residual foci.