A new approach to the treatment of malignant glioma is cytokine gene therapy to produce growth inhibitors in cells. Previously, we showed that human glioma cells selectively transfected with the gene of interferon (IFN)-beta and/or IFN-gamma by our novel liposomes tagged with monoclonal antibody against a glioma-associated antigen achieved a remarkable growth inhibition effect. In the present experiment, we demonstrated the effectiveness of gene therapy against glioma cells using liposomes bearing a plasmid containing the gene for tumor necrosis factor (TNF)-alpha. We also found that the effect of endogenous TNF-alpha was enhanced by treatment of IFN-gamma prior to the transfection with the TNF-alpha gene.