Mucopolysaccharidosis type VII (MPS VII) is an inherited lysosomal storage disease caused by insufficient β-glucuronidase (GUS). To provide gene therapy in a mutant mouse model of this disease, we have used a recombinant adeno-associated virus (rAAV) vector to deliver GUS cDNA to a variety of tissues. Although intravenous administration of vector produced therapeutic levels of GUS in the liver, delivery to the brain was inadequate. To improve delivery to the brain intrathecal injection of the vector into the cerebrospinal fluid was employed. This route of administration to either neonatal or adult mutant mice resulted in therapeutic levels of GUS in the brain and the elimination of storage granules in brain tissue.