Abstract: Objective From 1986 to 1993,102 mouth cavity caricinoma patients were treatecl by radiotnerapy,of them,51 were given irregular tractionated irradiation.They received 6Gy(A)→1.2Gy(B)→1.2Gy(A)→1.2GY(B)→1.2GY(A).After a rest of two days,the above cgcle was repeated.The total dose given was 64.8Gy/6W(10.8Gy/W×6).51 patients treated by conventional fractionation irradiation.The total dose given was 66Gy/6.5W(10Gy/W×6.5). Results :The improvement rate of short-term carative effect was 96.1% in the irregular tructionation irradiation graup,and 74.5% in thd conventional fraup Five-Year survival rate was 43.1% in the irregular tractionation irrodeation group,and 21.6% in the conventional one,with a remarkably difference between them(P＜0.05)