MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression through mRNA degradation or translation inhibition. It has not yet been clearly elucidated whether miRNAs participate in haematopoietic processes such as cell differentiation, apoptosis and maintenance of adequate levels of circulating blood cells. A human miRNA microarray was used to analyze miRNA expression in the erythropoietin-dependent cell line UT-7/EPO compared to other factor-dependent UT-7 cell lines. Among 324 human miRNAs, MIRN188, MIRN362 and MIRN210 levels were significantly elevated in UT-7/EPO cells, and stimulation with EPO in UT-7 cells increased the level of these three miRNAs. Notably, knockdown of MIRN210 in UT-7/EPO cells led to apoptosis. In mouse fetal liver cells, MIRN210 expression was twofold higher in TER-119-positive cells than in TER-119-negative cells. The expression of MIRN210 was elevated during erythroid maturation in vitro. These data suggest MIRN210 to be a member a new class of regulatory miRNAs that might play an important role in erythroid maturation.