Cell suspensions of LJH-OS were injected to nude mice subcutaneous. In tact tumor pieces, obtained from the third serial passage of subcutaneously growing xenografts, were implanted into the proximal tibia and the subcutaneous tissues of nude mice respetively. Animals were sacrificed and autopsied 4 and 7 weeks after transplantation and examined macroscopically for local tumor growth and metastasis. The tumor formation rate, the growth rate, the invasion and metastatic behavior of the orthotopic and ectopic xenografts were investigated and compared. We discovered the tumor with orthotopic transplatation had a faster growth rate than the s.c implantation. Tumors in the tibia invaded and destroyed the normal structure of the tibia bone, also infiltrated to the nearby tissues. The lung metastasis and reactive bone formation were observed only in the tibia transplatation model. It can be concluded the orthotopic transplantation of tumor tissue of the LJH-OS cell line into the tibia of nude mice resulted in local tumor growth and spontaneous metastasis which closely resembled the clinical situation. Therefore this model may be useful for experimental therapy studies and for investigations on the role of bone in regulating tumor growth, invasion and metastasis of osteosarcoma.