Objective: To establish a model of rat osteosarcoma in nude mice and to study its biological characteristics.Methods: Intact tumor pieces were inoculated into the right tibia of nude mice.The nude mice were killed at different time and the growth of tumor and metastasis were observed.Result: The tumor growth rate was 100%.From the first week to the second week after implantation it grew into outer tissue from tibia

and widely invaded Soft tissue on the third week.Pulmonary metastasis took place from the fourth week to the fifth week

and the nude mice died of cachexia and respiratory failure resulting from the widely whole pulmonary metastasis on the sixth week or so.Conclusion: The tumor growth rate is high.The model simulates the clinical process of human osteosarcoma

and could be a satisfactory model for studying osteosarcoma.