MicroRNAs (miRNAs) are a class of small endogenous non-coding RNAs that play important regulatory roles by targeting mRNAs for cleavage or translational repression. miRNAs act in diverse biological processes including development, cell growth, apoptosis, and hematopoiesis. The miRNA expression is associated with specific cytogenetic changes and can also be used to discriminate between the different subtypes of leukemia in acute lymphoblastic leukemia with common translocations, it is shown that the miRNAs have the potential to be used for clinical diagnosis and prognosis. We reviewed the roles of miRNA here with emphasis on their function in human leukemia and the mechanisms of the TEL/AML1, BCR/ABL, MLL/AF4 and TCF3/PBX1 oncoproteins on miRNAs expression in acute lymphoblastic leukemia.