The human cervix carcinoma (HeLa line) cells pre-irradiated by 60Co γ-rays were transinfected with Ad-CMV-p53. Survival fractions were measured by Clone Forming Unit. Cell cycle and the expression of p53 were detected by Flow Cytometry (FCM). Compared with the groups without pre-irradiation, the killing fractions on Hela cells pre-exposed to 60Co γ-rays significantly increased (Figs.1 and 2) the cycle of Hela cells pre-treated by 60Co γ-rays obviously changed (Fig.3). The pre-exposure of 60Co 7-rays strengthened the expression of p53 (Fig.4). Survival fractions were measured by Clone Forming Unit. Cell cycle and the expression of p53 were detected by Flow Cytometry (FCM). The human cervix carcinoma (HeLa line) cells pre-irradiated by 60Co γ-rays were transinfected with Ad- . Compared with the groups without pre-irradiation, the killing fractions on Hela cells pre-exposed to 60Co γ-rays significantly increased (Figs.1 and 2) the cycle of Hela cells pre-treated by 60Co γ-rays obviously changed .3). The pre-exposure of 60Co 7-rays strengthened the expression of p53 (Fig. 4).