Aim: Investigation of hematological illnesses identified by bone marrow analysis. Material and methods: 100 patients were investigated with complete blood count, peripheral blood smear with haemotological parameters like bleeding time (BT), clotting time (CT), reticulocyte count prior to bone marrow examination. Bone marrow aspiration was done using bone marrow aspiration needle under all aseptic precautions after giving local anaesthesia by 2% lidocaine hydrochloride. Bone marrow trephine biopsy was performed when the bone marrow aspirationyielded a bloody tap or dry tap and stained with hematoxylin and eosin stain. Prussian blue stain was used for iron staining. The slides were observed under the microscope and findings noted. Results: On bone marrow examination, hematological malignancies were found in 33(33%) cases, non-malignant haematological disorders were found in 55(55%) cases and normal marrow were in 12 cases (12%). Acute leukaemia (ALL, AML) were the most common malignant conditions, 17(17%) & 12(12%) respectively. The next common malignancies in this study were Chronic myelogenous leukaemia (CML) (2%) followed by myelodysplastic syndrome (1%) and Plasma cell dyscarsia (PCD) (1%). In present study out of 55 cases of non-malignant haematological disorders maximum number of cases were of nutritional anemia (35 Cases), outof which 17 patients had Dual Deficiency Anemia (DDA), 10 cases had Iron Deficiency Anemia (IDA), and 8 Megaloblastic anemia.Aplastic anemia in 17% cases and HLH in 3% cases. Conclusion: Bone marrow examination is a vital diagnostic procedure for identifying a wide range of hematological disorders. By analyzing the cellular composition and architecture of the bone marrow, clinicians can diagnose conditions such as leukemias, myelodysplastic syndromes, myeloproliferative neoplasms, multiple myeloma, aplastic anemia, and lymphomas. Accurate diagnosis is essential for guiding appropriate treatment strategies and improving patient outcomes.