Introduction. The characteristics of pathological clone cells in the Primary Myelofibrosis (PMF) strongly influence on the variability of the clinical course and prognosis. The main of them are type of driver mutation in JAK2, MPL or CALR genes ("clonal markers" (CM)), cytogenetic and epigenetic alterations. It is very important to provide the physicians necessary and sufficient information about the molecular profile of the disease to select the appropriate therapy for the patient.The aim of our study was to investigate mutational diversity in PMF patients from the North-West region of the Russian Federation and to estimate overall survival (OS) depending on the type of CM, cytogenetic and epigenetic features.Materials and methods. We examined 115 patients with PMF (45 male, 70 female). Median age was 59 years (range 19-82). The detection of V617F mutation of JAK2 was carried out for all the patients. JAK2(-) samples were tested for MPL gene 515 codon mutations and 9th exon mutations in the CALR gene. All patients underwent the analysis of mutations in EZH2, ASXL1 and IDH1 genes. Karyotype research was done for 47 patients with suitable bone marrow samples. Differences of mutation/karyotype occurrence in groups were assessed using the χ2 test. Survival curves were estimated by the method of Kaplan-Meier. Differences were considered as statistically significant with p-value