Context: Bone marrow examination is an important diagnostic tool widely used in various haematological and non-haematological disorders. Bone marrow evaluation may either confirm clinically suspected disease or may provide the previously unsuspected diagnosis.Objectives: To study the spectrum of lesions, comparison and evaluation of diagnostic efficacy of the bone marrow aspiration and bone marrow biopsy findings in various haematological and non-haematological disorders.Design: A prospective study on 100 cases of bone marrow aspiration and biopsy was conducted between January 2019 to June 2020. Conclusion:This study concludes that bone marrow aspiration and biopsy are complementary to each other in diagnosing various haematological and non-haematological disorders. Therefore, simultaneous evaluation of both ensures accurate diagnosis, and further management.