Introduction. Primary myelofibrosis (PM) and essential thrombocythemia (ET) are included into the group of Ph-negative myeloproliferative neoplasms (MPN) with similar changes, especially thrombocytosis in the complete blood count (CBC). Despite numerous studies in the field of MPN, the etiology and treatment options are still not determined. Objective. The aim of the study was the assessment of treatment results in patients with PM and ET. Material and Methods. 450 patients with PM and 176 patients with TE were diagnosed in Moldova by the peripheral blood moleculargenetic analysis and bone marrow biopsy. The study included 16 PM cases and 17 ET cases, who were treated with interferon alpha and followed up at the Institute of Oncology from Moldova between 2019-2022. Results. The median age of patients with PM was 38 years, and that one of patients with TE – 39 years. We achieved symptoms relief and CBC normalization in 33.3 % of cases with PM. Treatment was suspended in 33.3 % of cases with PM and only in 17.6 % of cases with ET. Interferon therapy combined with hydroxyurea was administered in 8.3 % of PM patients. The tumor process stabilization was achieved in 8.3 % of cases with PM. In the group of patients with ET, the CBC was recovered to normal in 64.8 % of cases, and the platelets count remained stable in 17.6 % of cases during the treatment. Conclusions. This study shows that interferon alpha is an effective treatment option for MPN, particularly in young people or in cases of intolerance to the other anticancer medications.