The number 01' patien ts with tongue carcinoma is increasing rapidly among young indiv idua ls in many parts of the worl d. Until now‘ most of studies were focused on the comparison malignancy wi th normal 01' dysplasia. There is little report of gene a lterations in normal to cancer , oral carcinogenesis. The purpose of present study is to evaluate the gene a ltc ration in every steps of oral carcinogenes is by DD- PCR. To induce tongue carcinoma in rat by 4- NQO. each dri nking water made 10ppm. 25ppm. 50ppm and control(o nly D.W without 4-NQO) . Specimens were classified into 4 groups s uch as co ntrol, I(mild & mocle rate dysplasia) , II(severe dysplasia and car cinoma in s itu) , III(carcinoma). Total RNA was ext racted and DD- PCR was performed using customized random primers. And to confïrmed t he results of DD-PCR‘ RT- PCR a nd real-time PCR with specific primers were carried out. There was phenotypic alteration in tongue 。f dosc a nd t imc dc pcndcnt man ncr. In gross examination, multiple papules, patch form or ulcerations were observed during 4 - NQO t reatment Hi s tologicall y, dysplasia was observed in 3 to 6 month and tumor formation in 6 to 8 month For DD-PCR, RT-PCR and real-time PCR, cyclophilin A, BAC RP23-372MB and BAC CH230-103E9 were differ entia lly expressed. Taken together, cyclophilin A has a role in all steps of oral carcinogenesis. BAC RP23-372N田is implica ted in carcinoma in s itu a nd BAC CH230-103E9 mRNA expression is assoicated with dysplasia and carcinom in s itu Conclus ively. some genes a re impli catcd a ll st eps of oral carci nogenesis, others are associated with one step, whi ch meant that genes are di fferentia lly expressed in every steps