Background and aim of work: NHL is a heterogeneous group of malignancies due to uncontrolled proliferation of B and T cells in the lymphoid organs. B-cell lymphomas are the more common type, with the most commonly encountered subtypes being diffuse large B-cell lymphoma and follicular lymphoma (Sikbola et al., 2007). In Egypt, NHL ranks the 3rd most common malignancy among all cancer types (Mokhtar, 2003); the purpose of the present work is to study the characteristics of BM involvement in Egyptian NHL patients with respect to incidence, histologic pattern and morphology of infiltration and its discordance with the histology of primary anatomic site. Subjects and methods: the study included 100 Egyptian NHL patients. The patients were subjected to CBC, Bone Marrow Aspirate, and trephine Bone marrow biopsy. Bone marrow specimens were examined by preparing histological sections from fixed biopsy specimens for morphological examination and immunohistochemical study for assessment of bone marrow infiltration. Results: BM biopsy showed involvement by lymphoma in 18 cases (18%). The incidence of involvement was higher in B-cell lymphomas (16/18), when compared to T-cell lymphomas (2/18), and the predominant pattern of involvement was interstitial infiltration (77.8%). DLBCL had the highest incidence in all the B-cell lymphomas. A discordant histology between BM and primary anatomic site was found in only one case. Conclusion: Proper staging in case of NHL using a reliable testing improves the prognosis of these patients by increasing or even changing the protocol of management for the positive patient.