Mutations of the p53 tumor suppressor gene are the most common molecular genetic abnormality to be described in ovarian cancer. To determine the feasibility of mutant p53 as a molecular target for gene therapy in ovarian cancer, we constructed an adenovirus vector containing the wild-type p53 gene. The ability of this adenovirus construct (Ad-CMV-p53) to express p53 protein was examined by Western blot analysis in the H358 lung cancer cell line, which has a homozygous deletion of the p53 gene. The ability of the adenovirus vector system to infect ovarian cancer cells was tested using an adenovirus containing the β-galactosidase reporter gene under the control of the CMV promoter (Ad-CMV-βgal). The ovarian cancer cell line 2774, which contains an Arg273His p53 mutation, was infected with Ad-CMV-βgal, and the infected cells were assayed for β-galactosidase activity after 24 hr. To test the ability of wild-type p53 to inhibit cell growth, the 2774 cell line was infected with Ad-CMV-p53 or Ad-CMV-βgal, and the effect of these agents on the growth of 2774 cells was determined using anin vitrogrowth inhibition assay. Western blot analysis of lysates from H358 cells infected with Ad-CMV-p53 showed expression of wild-type p53 protein. When 2774 cells were infected with Ad-CMV-βgal at a multiplicity of infection (m.o.i.) of 10 PFU/cell, >90% of cells showed β-galactosidase activity, demonstrating that these cells are capable of efficient infection by the adenovirus vector. Growth of 2774 cells infected with Ad-CMV-p53 was inhibited by >90% compared to noninfected cells. The ability of the adenovirus vector to mediate high-level expression of infected genes and the inhibitory effect of Ad-CMV-p53 on the 2774 cell line suggests that the Ad-CMV-p53 could be further developed into a therapeutic agent for ovarian cancer.