BACKGROUND: The relationship between obesity and graft-versus-host disease (GVHD) has been studied in both preclinical and clinical studies with varying results. OBJECTIVES: We aimed to investigate the impact of obesity, as measured by body mass index (BMI), on the incidence, severity, and response to therapy of GVHD in a contemporary cohort. STUDY DESIGN: We conducted a retrospective study of patients undergoing allogeneic hematopoietic cell transplant (HCT) for acute myelogenous leukemia and myelodysplastic syndrome between January 2010 and December 2021 at the Cleveland Clinic. Incidence, grade, organ involvement, and response to therapy of acute and chronic GVHD were compared between patients with obesity (BMI ≥30) and without obesity. Secondary outcomes included relapse, nonrelapse mortality (NRM), and overall survival (OS). RESULTS: 531 patients were identified, with a median follow-up of 19 months (range, 7-49). Mean (SD) BMI at time of HCT was 29.1 (6.3) kg/m CONCLUSION: There were no significant differences in incidence of GVHD among patients with and without obesity. Additional studies are needed to further understand potential differences in organ involvement.