The use of replicating viruses for cancer therapy (virotherapy) holds much promise.We reported previously that the live attenuated Edmonston B vaccine strain of measles virus (MV-Edm) had antineoplastic efficacy against hematological malignancies. In this study, we demonstrate that a recombinant MV-Edm, genetically engineered to express an inert soluble marker peptide (MV-hCEA), is potent against human epithelial ovarian cancer cells in vitro and in vivo. The virus was selectively oncolytic for ovarian tumor cells but caused minimal cytopathic damage on nontransformed ovarian surface epithelium and mesothelium. In contrast to nontransformed cells, the ovarian tumor cells expressed high levels of the measles virus receptor CD46. When injected directly into large established s.c. SKOV3ip.1 human epithelial ovarian xenografts in athymic mice, the virus induced complete regression of 80% of the tumors. i.p. administration of virus enhanced the median survival of mice with advanced i.p. SKOV3ip.1 tumors by >50 days. In addition, we could easily follow the kinetic profile of viral gene expression in the treated mice by determining serum levels of the virally encoded marker peptide (soluble human carcinoembryonic antigen). Trackable recombinant measles viruses warrant further investigation for therapy of ovarian cancer.