This is a single institution retrospective experience examining the effect of race and ethnicity on disease phenotype in myeloproliferative neoplasms. We demonstrate racial disparities in the outcomes of myeloproliferative neoplasm, with Caucasian ethnicities being relatively protected against cardiovascular thrombosisis and hemorrhagic complications. African Americans are the ethnic sub-group at highest risk of hemorrhagic complications. Background: The Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs) are characterized by an increased risk of thrombotic and hemorrhagic complications. Large retrospective studies have demonstrated racial disparities in MPN outcomes and attributed this to differences in access to health care. Utilizing a single institution experience, we report outcomes in patients with polycythemia vera (PV), essential thrombocythemia (ET), and myelofibrosis in relation to ethno-racial background. Patients and Methods: A total of 127 Caucasian (56%) and non-Caucasian (44%) adult patients with MPNs consecutively treated at the University of Illinois between 1990 and 2012 were examined in this retrospective study. Relationships between ethno-racial background and vascular complications, and disease transformation were evaluated using multivariate logistic regression models. Results: Non-Caucasian PV patients had an increased risk of vascular complications including cardiovascular thrombosis and hemorrhagic events, while Caucasian patients with PV and ET had a higher risk of progression to myelofibrosis. In a Cox proportional hazard regression analysis, Caucasian race emerged as an independent prognostic factor protective against cardiovascular thrombosis in PV and ET patients (hazard ratio, 0.2; 95% confidence interval, 0.03-0.9; P = .04) while age >60 years and prior thrombosis were significant risk factors in univariate analysis. Non-Caucasian race was also a significant risk factor in univariate analysis of hemorrhagic complications of PV and ET, and this was largely driven by African American ethnicity. Conclusion: This study shows for the first time that race can influence clinical outcomes in myeloproliferative neoplasms. Our findings highlight the need for greater representation of non-Caucasian patients in studies investigating vascular risk factors in MPNs. (C) 2016 Elsevier Inc. All rights reserved.