A method for evaluating the regrowth drug resistance in relapsed acute myelogenous leukemia (AML) was developed. Drug sensitivity and proliferation of leukemic cells in vitro were determined using leukemic cell colony forming unit (CUF L), MTT drug sensitive test, percentage of S phase cells in cell cycle (S %), fluorescent index (FI) and drug resistant index (DRI) by detecting intracellular daunorubicin, expression of P 170 glycoprotein by APAAP assay, and abundance of Bcl XL mRNA by semiquantitative reverse transcription polymerase chain reaction (RT PCR) methods. First, the correlation between scoring criteria and cell drug resistance and cell proliferation was investigated in newly untreated AML patients. Second, 20 patients with relapsed AML were marked. According to each tested result, its point (s) was scored. The results showed that among the 20 cases of replased AML, 9 were diagnosed as having regrowth drug resistance. It was concluded that the scoring method for regrowth drug resistance was first developed in AML. There was regrowth drug resistance in relapsed AML; clinically circumventing it would be of extreme significance for establishment of new approaches to the treatment in AML. Drug resistance and proliferation of leukemic cells in vitro were determined using the leukemic cell colony forming unit (CUF L), MTT drug sensitive test, percentage of S phase Cells in cell cycle (S %), fluorescent index (FI) and drug resistant index (DRI) by detecting intracellular daunorubicin, expression of P 170 glycoprotein by APAAP assay, and abundance of Bcl XL mRNA by semiquantitative reverse transcription polymerase chain reaction (RT PCR) methods. First, the impedance between scoring criteria and cell drug resistance and cell proliferation was investigated in newly untreated AML patients. Second, 20 patients with relapsed AML were marked. According to each tested result, its point (s) was scored. The results showed that among the 20 cases of replased AML, 9 were diagnosed as having regrowth drug resistance. It was disclosed that The scoring method for regrowth drug resistance was first developed in AML. There was regrowth drug resistance in relapsed AML; clinically circumventing it would be of extreme significance for establishment of new approaches to the treatment in AML.