International audienceMicro RNA (miRNA) are small non-coding RNA molecules which have a post-transcriptional inhibitory regulation function, e.g. in megakaryopoiesis. A characteristic of Philadelphia chromosome-negative myeloproliferative neoplasm (Ph MPN) is the abundance of morphologically aberrant megakaryocytes. Based on previously published in vitro megakaryocytic differentiation assay data, we selected miRNA 10a, 17-5p, 20a and 126 and potential target proteins (HOXA1, RUNX1) for analysis of laser-microdissected bone marrow megakaryocytes from Ph MPN and controls ( = 66). Furthermore, we tested a potential influence of cytoreductive treatment on miRNA expression in bone marrow cells during the course of Ph MPN ( = 18). In summary, miRNA 17-5p, 20a and 126 are constitutively expressed in Ph MPN megakaryopoiesis while low or absent miRNA 10a appeared to correlate with strong megakaryocytic HOXA1 protein expression. No association to thrombocytosis, JAK2 mutations or cytoreductive treatment (bone marrow cells) were observed