Introduction: Bone marrow is not only a reservoir of stem cells but also provides microenvironment for proliferation and development of precursors and regulate the release of mature cells in to circulation. Bone is commonly involved in metastatic tumors and rank third most common site of metastasis after lung and liver. Metastasis may be present in the bone marrow without any abnormalities recognized in bone scans, radiographic pictures, serum chemistry and hematological parameters and remain the only procedure to diagnose the presence of metastatic tumor. AIMS: To study the clinical features&characteristics of BM involvement in NHL& HL cases with respect to morphology of infiltration for staging and their prognosis. Materials and Method: A prospective study was conducted on 38cases who had not received any prior specific treatment (chemotherapy and radiotherapy) for both Hodgkin's and non-Hodgkin's lymphoma from northern India, . Out of 38 cases Hodgkin's lymphoma were 08 cases and non- Hodgkin's lymphoma were 30 cases . All cases were examined clinically and later on Bone marrow aspiration and Bone marrow biopsy was obtained from the posterior superior iliac spine. The biopsies were fixed in 10% buffered formalin solution and decalcified using 10% formal - formic acid for 4 - 6 h followed by routine processing. The serial sections were stained by hematoxylin and eosin and reticulin stains. The smears were air dried and immediately fixed in methanol for one of the Romanowsky stain (We used Leishman stain and May-Grunwald Geimsa stain) for cellularity and morphology1. Serial aspiration and biopsies were done in all cases of Hodgkin's and non-Hodgkin's lymphoma Observations: The most prominent clinical feature was cervical lymphadenopathy. Patients with advanced disease had systemic features like fever, weight loss and hepatosplenomegaly. The incidence of marrow involvement in known case of Hodgkin's and non-Hodgkin's lymphoma was 25% and 43.33% respectively. The incidence of bone marrow involvement was found in mixed cellularity and in lymphocyte depletion type of Hodgkin Lymphoma cases and the pattern of involvement of bone marrow was diffuse in all the cases. The extent of marrow involvement was greatest in Non Hodgkin lymphomas that exhibit a diffuse pattern of infiltration. In thirteen cases (43.33%) of bone marrow involvement, seven cases (53.8%) showed presence of neoplastic cells in both aspiration and biopsy while six cases (46.2%) showed presence of neoplastic cells in bone marrow biopsy. Serial aspiration and biopsies revealed that both cases (100%) of Hodgkin's lymphoma improved with systemic chemotherapy, while five cases (38.46%) of non-Hodgkin's lymphoma showed clearance of bone marrow by the neoplastic cells on completion of chemotherapy. Conclusion: In all the cases, which infiltrated to bone marrow, histological grades were same as in the FNAC / Histopathology examination at the time of diagnosis from the primary site. Bone marrow aspiration and biopsy were performed as complimentary procedures. But Bone marrow biopsy was found superior to bone marrow aspiration.. It was also helpful in the management strategy of the disease as well as to see the response of the therapy by serial aspiration and biopsies10. It was found that in five cases (38.46%) of non-Hodgkin's lymphoma bone marrow showed clearance of tumor cells after completion of chemotherapy.