INTRODUCTION: The main terms for typical BCR::ABL1-negative myeloproliferative neoplasms (MPNs) are essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF). Monocytes in MPN patients are involved in their inflammation and form an important part of the pathophysiology of MPN patients. METHODS: We used flow cytometry to study the immunophenotype of bone marrow monocytes from MPN patients (N = 118) and to correlate it with clinical parameters (including genetics, pathology, blood counts, personal information). RESULTS: The results showed that bone marrow monocyte cells from MPN patients expressed the inflammation-related marker CD16 at higher levels than healthy controls. Second, bone marrow monocytes from Overt-PMF patients expressed CD11b at higher levels than monocytes from ET patients. Finally, certain specific monocyte subpopulations in MPN patients correlated with their clinical parameters. For example, in patients with ET and PMF, CD64+ monocytes were positively correlated with WBC and LDH. In PMF patients, the proportion of bone marrow monocytes was positively correlated with the grade of myelofibrosis, and CD15+ monocytes positively correlated with WBC and IPSS scores. CONCLUSION: Our results provide insights into the immune microenvironment of MPNs based on immunophenotypic features and provide potential immune markers for MPNs occurrence and development.