MicroRNAs (MiRNAs) are a class of small non-coding regulatory RNAs that repress protein expression at the posttranscriptional level and play important roles in hematopoiesis processes. MiR-146a is a miRNA that is thought to regulate physiological and pathophysiological pathways in hematopoietic cells. In this review, we focus on recent progress in analyzing the functional roles of miR-146a in normal hematopoiesis and hematopoietic disease. We suggest that manipulation of miR-146a expression may represent a potential new therapy for several hematopoietic diseases, and may further serve as a biomarker for diagnosis, prevention, and treatment of such disease.