This study aimed to investigate clinical characteristics and prognostic significance of activation-induced cytidine deaminase (AID) gene, miR-181b and miR-155 expression inde novoadult B-cell acute lymphoblastic leukemia (B-ALL) patients. Results showed that AID and miR-155 expression were higher in B-ALL patients than healthy controls, while miR-181b expression was lower in B-ALL patients. In addition, Ph+B-ALLs had higher AID expression than Ph-B-ALLs, and its high expression was associated with BCR-ABL. Moreover, B-ALL patients with AIDhighor miR-181blowexpression had a shorter overall survival (OS). AIDhighwith miR-181blow, AIDhighwith miR-155low, miR-181blow, miR-155low, AIDhighwith miR-181blowand miR-155lowexpression were associated with shorter OS. Combination of the three molecules are more accurate predictors for unfavorable OS compared with univariate group. Therefore, AID, miR-181b and miR-155 provide clinical prognosis of adultde novoB-ALL patients and may refine their molecular risk classification. [ABSTRACT FROM AUTHOR]