Abstract: Objective 　To study the gene expression disparity of giant cell tumor with ( GCT) cDNA mi2 croarray. Methods 　Total RNA of 8 f resh GCT specimens and 4 normal bony callus were ext racted, puri2 fied to mRNA and then reverse t ranscripted to cDNA respectively. cDNA expression microarray with a set of 8 064 human genes was conducted to analysis the difference among the samples and the compari2 son. The hybridization signals were scanned by Amersham Pharmacia Gen Ⅲ and analyzed by sof tware Image Quant . Results 　Significant different expressed genes were found between the GCT samples and normal bony callus ( P < 0. 01), Forty 2 seven genes differentially expressed for above 5 folds in GCT spec2 imens were identified, with twenty2five genes up2regulating and twenty2two down2regulating which are mainly ext ra cellular mat rix regulating genes, oncogene and cytokine genes. Conclusion 　cDNA microarray is a powerful tool to identify genes associated with GCT, which facilitates the pathogenesy elucidation, diagnosis and t reatment of GCT.