Objective To investigate the expression of 90K mRNA and protein in human brain astrocytomas.Methods The expression of 90K mRNA in human normal brain tissue and astrocytoma tissue was detected by RT-PCR; The expression of 90K protein in human normal brain tissue and astrocytoma tissue was detected by WB.Results RT-PCR reveal that 90K mRNA was lowly expressed in normal human brain tissues (0.116±0.017).The 90K mRNA expression was significantly higher in astrocytomas (0.407±0.151) than that in normal human brain tissues (t=6.065, P<0.05), and significantly higher in high grade astrocytomas (WHO Ⅲ-Ⅳ) (0.516±0.128) than in low grade (WHOⅠ-Ⅱ) (0.295±0.067) (t=8.138, P<0.05).WB reveal that 90K protein was lowly expressed in normal human brain tissues (0.291±0.064).The 90K protein expression was significantly higher in astrocytomas (1.163±0.391) than that in normal human brain tissues (t=15.68, P<0.05), and significantly higher in high grade astrocytomas (1.415±0.318) than in low grade (0.902±0.272) (t=6.539, P<0.05).The expression of 90K mRNA was in accordance with the expression of 90K protein both in astrocytomas and normal human brain tissues.Conclusions 90K expressed positive in astrocytomas.The expression of 90K is higher in higher grade astrocytomas.90 K may contribute to occurrence and progression of astrocytomas.90K protein may be a astrocytomas-associated antigen and target antigen in immunotherapy.