Expression and its clinical significance of heat shock protein gp96 in human osteosarcoma. The aim of the study was to observe the expression of heat shock protein gp96 (HSPgp96) and explore its clinical significance in human osteosarcoma. <br />The expression of HSPgp96 was studied in 44 osteosarcoma tissues including 24 osteoblastic sarcoma and 20 chondroblastic sarcoma, normal tissues adjacent to the sarcomas were evaluated simultaneously. <br />The immunoreactivity was found positive in all osteosarcoma tissues (44/44), but 21.5% (9/44) in normal tissues. HSPgp96 was mainly expressed in cytoplasm of osteoblastic sarcoma, while in nucleus of chondroblastic sarcoma. HSPgp96 immunolabelling had significantly correlation with the Price degree (P 0.05), and histological subtypes (P >0.05). <br />The HSPgp96 is highly expressed in osteosarcoma and has different immunolocalization during two subtypes of osteosarcoma. The immunopositivity is significantly higher in tumors with lower differentiation. The research implies that HSPgp96 may play acontributive role on the pathogenesis and development in human osteosarcoma, and there is hope in its application in determining the degree of malignancy of cancer and utilization as atarget for tumor immunity. Keywords: heat shock protein gp96, immunoreactivity, osteoblastic sarcoma, chondroblastic sarcoma.