Using cDNA from normal human primary cultures of nasopharyngeal epithelial cells as tester amplicon and cDNA from nasopharyngeal carcinoma(NPC) cell line HNE1 as driver amplicon, four differential cDNA fragments were isolated by cDNA representational difference analysis(RDA).While these differential cDNA fragments were hybridized to amplicons by DNA blot, it was found that they really came from the tester amplicon.In addition,RNA blot also revealed that the differentially expressed fragments were not expressed or down-regulated in the NPC HNE1 cells;and sequence analysis also indicated that those differentially expressed fragments may include tumor suppressor gene relative to NPC. Therefore,it shows that the cDNA RDA is an effective，sentitive and specific method for screening the candidates of tumor supressor gene.