Objective : Endometrial carcinoma is the most common gynecological malignant disease in industrialized countries. However, the molecular bases for endometrial tumoriogenesis are not clearly elucidated. Our hypothesis is that there may be some difference in gene expression patterns between normal endometrium and endometrial cancer lesion. In this study, we analyzed the difference of gene expression profile with cDNA microarray. Methods : Normal endometrial tissues and cancer lesions were gathered from three patient with endometrioid endometrial cancer. cDNA microarray technique (KNU 4.8K chip) was applied to screen the different gene expression profiles. Results : Many genes such as interleukin-1 receptor-associated kinase 1 (IRAK1), bifunctional apoptosis regulator (BFAR), paraneoplastic antigen MA2 (PNMA2), zinc finger protein 257 (ZNF257), ras homolog gene family, member F (in filopodia) (ARHF), cell division cycle 27 (CDC27) were over-expressed in the endometrial cancer tissue. The genes were down-regulated in the endometrial cancer samples included fibronectin 1 (FN1), meiotic checkpoint regulator (MCPR), transforming growth factor beta-stimulated protein TSC-22 (TSC22), programmed cell death 4 (neoplastic transformation inhibitor) (PDCD4), transcript variant 2, matrix metalloproteinase 2 (MMP2), insulin-like growth factor binding protein 4 (IGFBP4), retinoblastoma binding protein 7 (RBBP7), insulin-like growth factor binding protein 3 (IGFBP3), downregulated in ovarian cancer 1 (DOC1). Conclusion : The result of this analysis supports the hypothesis that the endometrial cancer tissue has distinct gene expression profile from normal endometium. But, the vaildation of gene expression with RT-PCR and the further study are needed.