Grafting genetically-modified cells into the brain is a promising approach to address fundamental and clinical issues in neurobiology. Despite recent substantial progress, most of the methods used for introducing DNA sequences into donor cells result in weak efficacy or transient gene expression after transplantation. We tested whether the use of adenovirus as the vector for foreign genes avoided these problems. A replication-defective adenovirus vector carrying a reporter gene encoding for beta-galactosidase was used to transfect primary astrocytes. After grafting into various brain structures, transfected cells exhibited robust survival and expressed the transgene for at least five months. These results demonstrate the advantage of adenovirus-mediated gene transfer for prolonged transgene expression in grafted primary cells.