Objective: To investigate the inhibitory effect and IC50(50% inhibiting concentration) of the recombinant adenoviral p53 gene (rAdp53) in colorectal cancer cells in vitro and to guide clinical practice. Methods: We evaluated the efficiency(IC50)of the rAdp53 and six kinds of anti-cancer drugs(5-fluorouracil, tegafur, mitomycin c, cisplatin, oxaliplatin, paclitaxel) in human colorectal cancer cell line-174 through the cell culture and MTT chemosensitivity assay to make sure the anti-cancer capability of rAdp53. Expression of p53 protein in transfection cells of colorectal cancer line-174 with rAdp53 was evaluated by immunohistochemical staining. Results: The rAdp53 is a dose- and time-dependent anti-cancer drug, its IC50 is 5.73×1011 VP/ml, but its effect was not obvious when compared with other anti-cancer drugs. In control group, the immunohistochemistry stain was negative. However, rAd-p53 of five different concentrations were all positive in infected colorectal cancer cells with rAd-p53 and the earliest positive result would present 24 hours after infection. Conclusion: The rAdp53 has good anti-cancer efficacy is colorectal cancer cell line-174 in vitro. But its anti-cancer efficacy was less than those of the classical chemical medicine mitomycin c, 5-fluorouracil and cisplatin etc., when it was used alone. Objective: To investigate the inhibitory effect and IC50 (50% inhibiting concentration) of the recombinant adenoviral p53 gene (rAdp53) in colorectal cancer cells in vitro and to guide clinical practice. Methods: We evaluated the efficiency (IC50) of the rAdp53 and six like anti-cancer drugs (5-fluorouracil, tegafur, mitomycin c, cisplatin, oxaliplatin, paclitaxel) in human colorectal cancer cell line-174 through the cell culture and MTT chemosensitivity assay to make sure the anti-cancer capability of rAdp53. Expression of p53 protein in transfection cells of colorectal cancer line-174 with rAdp53 was evaluated by immunohistochemical staining. Results: The rAdp53 is a dose- and time-dependent anti-cancer drug, its IC50 is 5.73 × 1011 VP / ml, but its effect was not obvious when compared with other anti-cancer drugs. In control group, the immunohistochemistry stain was negative. However, rAd-p53 of five different concentrations were all positive in infected colorectal cancer cells with rA d-p53 and the earliest positive result would present for 24 hours after infection. Conclusion: The rAdp53 has good anti-cancer efficacy is colorectal cancer cell line-174 in vitro. But its anti-cancer efficacy was less than those of the classical chemical medicine mitomycin c, 5-fluorouracil and cisplatin etc., when it was used alone.