Mutations of the tumor-suppressor gene p53 have been found in 30-50% cases of hepatocellular carcinoma (HCC). In this study, E1-negative adenoviral vector encoding wild-type p53 under the control of the human cytomegalovirus promoter (AdCMV-p53w) was constructed to evaluate its therapeutic efficacy against tumor nodules developing after injection of HuH7 cell lines in ten nude mice. When each nodule had reached 10 mm in perpendicular diameter, 1.5 x 10⁸ pfu of AdCMV-p53w per session was injected intratumorally as follows: In group I (n=3), five sessions were injected every other day. In group II (n=3), only one session. Group III (n=4) as negative controls. The mice were sacrificed at 28 days post AdCMV-p53w injection. Tumor growth was significantly suppressed and delayed in group I and II compared to group III as compared by tumor volume at the end of observation. These results suggest that AdCMV-p53w may not only be effective in treating HCCs expressing mutant p53, but also useful as a local injectable gene therapy.