Background: Body composition parameters are associated with long-term health outcomes. We assessed longitudinal body composition changes in diffuse large B-cell lymphoma (DLBCL) survivors and identified clinical variables associated with the long-termdevelopment of sarcopenia and visceral obesity. Methods: A retrospective cohort of United States veterans with DLBCL treated with cyclophosphamide, doxorubicin, vincristine, and prednisone, with or without rituximab, was assembled. Muscle, subcutaneous fat, and visceral fat areas were measured with computed tomography analysis. Data were analyzed with repeated-measures analysis of variance and logistic regression. All statistical tests were two-sided. Results: Three hundred forty-two patients were included. Muscle area initially decreased during treatment, then returned to baseline by 24 months after treatment. Subcutaneous fat area increased from baseline by 6.5% (95% confidence interval [CI] = 2.6% to 10.5%) during treatment and by 21.4% (95% CI=15.7% to 27.2%) by 24 months after treatment. Visceral fat area increased from baseline by 4.5% (95% CI = -0.9% to 9.9%) during treatment and by 21.6% (95% CI=14.8% to 28.4%) by 24 months after treatment. Variables associated with long-term development of sarcopenia included: baseline sarcopenia (adjusted odds ratio [aOR] = 17.21, 95% CI=8.48 to 34.94), older than age 60 years (aOR = 2.93, 95% CI=1.46 to 5.88), and weight loss greater than 5% during treatment (aOR = 2.40, 95% CI=1.12 to 5.14). Variables associated with long-termvisceral fat gain included: weight gain greater than 5% during treatment (aOR = 4.60, 95% CI=2.42 to 8.74). Conclusions: DLBCL survivors undergo unfavorable long-term body composition changes. Patients at risk for the long-term development of sarcopenia or visceral obesity can be identified based on clinical risk factors and targeted for lifestyle interventions.