Objective To investigate the role of FAT10 in the occurrence and development of primary osteosarcoma,and to provide a new target for biological therapy of primary osteosarcoma.Methods FT-PCR was used to detect the expression of FAT10 mRNA in 22 primary osteosarcoma fresh tissues,22 para-osteosarcoma fresh tissues and 12 benign bone tissues.ResultsPositive rates of FAT10 mRNA in primary osteosarcoma tissues,para-osteosarcoma tissues and benign bone control tissues were 81.82%(18/22),13.64%(3/22)and 8.33%(1/12)respectively.No significant difference was found between para-osteosarcoma bone tissues and benign bone tissues in the positive rates of FAT10 mRNA(P0.05);significant difference was found between primary osteosarcoma tissue and benign bone tissues in the positive rates of FAT10 mRNA(P0.05);significant difference was found between primary osteosarcoma tissue and para-osteosarcoma bone tissues in positive rates of FAT10 mRNA(P0.05).Conclusions Expression of FAT10 mRNA is highly up-regulated in primary osteosarcoma.FAT10 can be used as an index to diagnosis primary osteosarcoma tissues.It may be a new target for biological therapy of primary osteosarcoma.