Background/Aims: MicroRNAs (miRNAs) play an important role in cellular differentiation and cancer pathogenesis. However, their role in promoting the malignant phenotype of myeloproliferative diseases and their importance for differential diagnosis of early-stage chronic myeloproliferative diseases (CMPDs) remains widely obscure. Methods: In this study, we systematically evaluated the differential expression of miRNAs previously described to be associated with myelopoiesis and myeloproliferative pathogenesis by quantitative RT-PCR in polycythemia vera, essential thrombocythemia, early primary myelofibrosis (PMF) and normal hematopoiesis. Our goal was to establish certain miRNAs as potential markers for CMPDs to facilitate the differentiation between these diseases and to further investigate molecular differences between the subtypes of myeloproliferative neoplasia. Results: An aberrant expression of miRNAs 10a and 150 could be demonstrated for essential thrombocythemia and PMF as well as for polycythemia vera and PMF, respectively. The expression of miR-150 could further be shown to correlate with both JAK2 allele burden and peripheral blood counts. Conclusion: Thus, the miRNAs investigated in this study seem to be potential marker oncomiRs in the differential diagnosis of CMPDs and possibly hold potential for the elucidation of a JAK2-independent mechanism of pathogenesis.