Therapeutic cells producing amphotropic retrovirus, which are able to transduce in vivo thymidine kinase gene of Herpes simplex virus were prepared. Single-cell clone cells with high virus productivity (PA-3 17JH5c113) were obtained by cell cloning. The cells were found free of replication competent retrovirus, they were non-tumorigenic in xenogeneic host and highly sensitive to ganciclovir treatment in vitro and in vivo. The therapeutic efficacy of PA-317JH5c113 cells was tested in rat brain tumor model. Increase in survival in the group of treated versus untreated rats was observed. Therefore, these cells are suitable for application in human clinical trial.