Ruxolitinib as a JAK1 and JAK2 inhibitor drug has recently been approved for the treatment of patients with high-or intermediate-risk myelofibrosis with symptomatic splenomegaly. Clinical development of ruxolitinib has currently focused on the Ph* negative myeloproliferative neoplastic disorders (MPN). The aim of this study is to assess the impact of ruxolitinib treatment on the clinical course of Ph* negative myeloproliferative disorders. Forty-three patients who were under ruxolitinib treatment and followed-up between years 1987-2015 in Hacettepe University Medical School Hematology Clinic and Ondokuz Mayis University Hematology Clinic with myeloproliferative disease without Philadephia chromosome translocation were retrospectively analyzed. The constitutional symptoms were decreased in 97% of patients after ruxolitinib treatment. The mean spleen sizes before and after ruxolitinib treatment were 229 +/- 35 versus 202 +/- 31 mm, respectively (p<0.001). In this study, we observed a reduction in spleen size after ruxolitinib treatment in Turkish patients with MPN and this reduction was statistically significant. Moreover, nearly all of the MPN patients' constitutional symptoms were improved. Those observations are concordant with other geographical MPN data obtained from different countries. Further experimental and clinical studies into the efficacy and safety of ruxolitinib in patients with MPN are necessary to elucidate its role in special subgroups of MPN patients, such as patients undergoing hematopoietic stem cell transplantation and the patients with vascular disorders such as hepatoportal thrombosis.