In this study we show that recombinant adenovirus can augment hypoxanthine-guanine phosphoribosyltransferase (HPRT) levels in the central nervous system (CNS) of HPRT-deficient mice. Recombinant adenovirus containing the cDNA for rat HPRT (rHPRT) expressed from the Rous sarcoma virus LTR (RSV LTR) was constructed (AdRSVrHPRT). AdRSVrHPRT was injected into the right caudate nucleus of 7-week-old HPRT-deficient mice. Brains were analyzed for gene transfer, transgene expression and function by DNA PCR, in situ RNA hybridization, and enzyme bioactivity. The results show that rHPRT cDNA delivered by an adenoviral vector can augment HPRT levels in brain tissue and documents the utility of gene transfer to restore HPRT activity in an HPRT-deficient CNS.