Introduction :– The histiocytosis are rare disorders characterized by the accumulation of cells thought to be derived from dendritic cells (DCs) or macrophages. Their clinical behavior ranges from mild to disseminated and, sometimes, life–threatening forms. Histiocytosis are a group of uncommon disorders characterized by proliferation of cells of the mononuclear phagocyte system and the dendritic system. Each of the histiocytosis of childhood is characterized by localized or generalized, reactive or neoplastic proliferation of cells . Aim: Aim of this study was to do differential diagnosis of Histiocytic disorder on the basis of morphological changes in bone marrow. Method and material – Prospective study, carried out in Department of Pathology from January 2014 to March 2019. A total of 20 cases were studied. Bone marrow examination done in department of pathology and relevant clinical details of the patients diagnosed as Histiocytic discords were collected. Hemograms were done in all cases. Special stains (PAS ) were done whenever required. Result :–The age of these cases ranged from 3 months to 12 years. There were 09 males and 11 females. Pathological diagnosis was made on bone marrow aspiration. Four cases of Langerhans cell histiocytosis (LCH), 11 cases of Hemophagocytic syndrome, 01 case of Hemophagocytic lymphohistiocytic disorder (HLH) and 04 cases of Granulomatous disorder were diagnosed on the basis of bone marrow morphology and relevant clinical history and investigations. Conclusion :– we concluded that on the basis of bone marrow morphology and clinical features differential diagnosis of Histiocytic disorder is possible