Objective: Bone marrow (BM) involvement is one of the mostimportant prognostic factors in lymphoma patients. Therefore,it is important to determine the presence of BM involvement inlymphoma patients at the time of diagnosis. Bone marrow biopsy(BMB) is still accepted as the gold standard for evaluating themarrow but it is painful and invasive. In this retrospective study,we aimed to evaluate the role of positron emission tomographycombined with computed tomography (PET/CT) in evaluating theBM involvement in lymphoma patients at the initial staging.Patients and Methods: The patients who were evaluatedby PET/CT and bone marrow biopsy at time of diagnosis wereenrolled in the study.Results: The overall sensitivity of PET/CT in demonstratingBM involvement was 65.8%, and the specificity was 89.4%. Inthe subgroup analysis of 176 Hodgkin lymphoma (HL) patients,the sensitivity and specificity of the PET/CT were 81% and84% respectively. Negative predictive value was 98%. In 201diffuse large B cell lymphoma (DLBCL) patients, the sensitivityand specificity of the test were 91.3% and 94.3%, respectively.Negative predictive value was 98.8%.Conclusion: PET/CT is an accurate and complementarymodality with high specificity and sensitivity in detecting BMinfiltration in HL and DLBCL patients.