To evaluate the value of bone marrow aspirates in assessing bone marrow involvement by B cell lymphoma. Subjects and Methods: Cross-section description of B-cell lymphoma from January 2019 to December 2020 at Blood Transfusion Hematology Hospital. Results: The incidence of bone marrow involvement was 64,8%. Bone marrow involvement was present in 80,0% of low-grade B-cell lymphomas and 40,0% of high-grade variants. The agreement level of bone marrow biopsy and bone marrow aspirate was 78,2%, and the overall sensitivity and specificity were 81,0% and 73,3%, respectively. When considering only the indolent B-cell lymphoma, the sensitivity of bone marrow aspiration was 86,4%, and the specificity was 73,3%. In contrast, the sensitivity and specificity were 65,0% and 73,3%, respectively, in the aggressive B-cell lymphoma. Conclusion: Bone marrow aspirate with low sensitivity and specificity, cannot replace bone marrow biopsy in the evaluation of bone marrow involvement by lymphoma. Bone marrow aspirate plays a role in evaluating lymphoma morphology as well as associated myelodysplasia.