This study was undertaken to establish the more reasonable criteria for diagnosis of acute myeloid leukemia (AML). 82 cases diagnosed initially or finally as AML were analyzed with morphology, immunology and cytogenetics (MIC). The results revealed that 89.0% of the pretherapy morphology conformed to MIC and 93.9% of the immunology conformed to it. 4 cases with hybrid acute leukemia (HAL), one case with acute undifferentiated leukemia (AUL) and one case with acute B-Acute lymphocytic leukemia were confirmed with MIC. The positive expression of myeloid markers on samples from 76 cases of AML was followed by CD33 > CD13 > CD65, SI6 > CD15 > CD11b > CD14, but not specific for AML subtypes. The lymphoid antigens CD2, CD7, CD10 and CD19 were positive in minority of the cases of AML, but CD2+ and CD7+ were easily found in M3 and M1 speerately. 55.4% of the patients with AML in this group showed abnormality in cytogenetics. Typical t(8;21) or its variants was found in 14/24 cases of M2 and one case of M1; t(7;11) (P15;P15) in one case of M2; t(15;17) in 4/7 cases of M3; and inv(16) in one case of M4E0. It is shown that MIC classificassion is more helpful than any signgle one of the three in diagnosis of AML, especially of HAL, AUL, Mo.