A diagnosis of round cell tumor of bone, not otherwise specified, is clearly unacceptable because of fundamental difference in therapy and in prognosis. Thirty six cases presented histologically with the picture of undifferentiated round cell tumor of bone were studied for proper cell typing using special stain (PAS), histochemical staining for alkaline phosphatase and indirect immunoperoxidase technique (ABC) with a panel of antibodies for leukocyte common antigen (LCA), S-100 protein, vimentin, broad-spectrum cytokeratin and Neuron Specific Enolase (NSE). Results showed primary non-Hodgkin's lymphoma in 9 cases, round cell osteosarcoma in one case, Ewing’s sarcoma in 14 cases, mesenchymal chondrosarcoma in one case, metastatic neuroblastoma in 4 cases and metastatic small cell carcinoma in 7 cases. The findings confirm the need of histochemical and immunologic markers as an adjuvant for screening such group of bone neoplasms for exact typing and proper management.