The publication contains materials of the reports presented at the II Conference “Current Issues of Diagnosis and Treatment of Ph-Negative and Ph-Positive Myeloproliferative Neoplasms” held from 15 to 16 March 2019 at the National Research Center for Hematology (Moscow). The conference was organized to enable professional communication of the clinicians specializing in the treatment of myeloproliferative neoplasms (MPN), and the researchers in the related fields as well as to allow the exchange of views on the implementation of current diagnosis and treatment methods in Ph-negative and Ph-positive MPNs. Reports covered a wide range of rare and non-standard settings. Of particular importance was the opportunity to debate them in detail at panel discussions and interactive sessions. This format of the conference allowed to provide expert opinions in the present publication. It emphasizes the importance of complex diagnosis in MPN using morphological examination of bone marrow core biopsy samples and molecular genetic testing. Accordingly, the second day of the conference was devoted to a thorough analysis of the morphological characteristics of the cases presented and based on bone marrow core biopsy samples.