Background: Pancytopenia is characterized by Anemia, Leukopenia & Thrombocytopenia. It is very often seen in day to day practice and requires thorough investigation to know the cause of Pancytopenia for timely and early management to improve the prognosis. Material and Methods: This study was conducted in the Department of Pathology Malla Reddy Institute of Medical Sciences over a period of 2 years and six months from January 2017 to June 2019.Patients were in the age group of 18 months to 65 years. The ratio of male to female patients was 1:1.4. 109 patients were evaluated by Bone Marrow Aspiration cytology, complete blood picture by automated counter, which was confirmed by manual blood count along with peripheral blood examination, to establish the etiology. 43 patients who fulfilled the criteria for a diagnosis of pancytopenia were included in the study. The as patients underwent several diagnostic tests hemogram, biochemical test like serum B12,serum folic acid, serum ferritin, total iron binding capacity. Bone Marrow Aspiration cytology and Bone marrow biopsy were done. Routine Giemsa stain as well as cytochemical stains like Pearls stain, Reticulin stain and Periodic Acid Schiff test, were carried out on the bone marrow material. Results: In the present study, the commonest cause of pancytopenia was found to be Megaloblatic Anemia (67.4%) followed by Hypoplastic Anemia (24.4%); the least common causes being infections (Malaria 2.3%), Aleukemic Leukemia (2.3%), Myelofibrosis (2.3%) and Myelodysplastic Syndrome (2.3%). Conclusion:The majority of patients with pancytopenia are diagnosed by Bone Marrow Aspiration as an adjunct to clinical history, clinical examination, peripheral blood examination, hemogram and biochemical examination. Bone Marrow Aspiration cytology is an important diagnostic tool to establish unequivocally the cause of pancytopenia.