Fabry disease is an X-linked recessive inborn metabolic disorder characterized by systemic and vascular accumulation of globotriaosylceramide (Gb(3)) caused by a deficiency of the lysosomal enzyme alpha-galactosidase A (alpha-gal A). The condition is associated with an increased morbidity and mortality due to renal failure, cardiac disease, and early onset of stroke. Hemizygous males are primarily affected clinically with variable expression in heterozygous females. Gene-therapy trials have been initiated recently in alpha-gal A knockout mouse models of Fabry disease by using a variety of viral vectors. In the present investigation we administered single i.v. injections of 1 x 10(10) genomes of recombinant adeno-associated virus (rAAV) encoding the human alpha-gal A gene driven by a modified chicken beta-actin (CAG) promoter to alpha-gal A knockout (Fabry) mice. Transgenic mice were analyzed for expression of alpha-gal A activity and Gb(3) levels in liver, kidney, heart, spleen, small intestine, lung, and brain. Administration of the rAAV-CAG-hAGA vector resulted in stable expression of alpha-gal A in organs of the Fabry mice for >6 months. alpha-Gal A activity in the organs became equal to or higher than that of wild-type mice. Accumulated Gb(3) in the liver, heart, and spleen was reduced to that of wild-type mice with lesser but significant reductions in kidney, lung, and small intestine. Injection of the rAAV-CAG-hAGA construct into skeletal muscle did not result in expression of alpha-gal A in it or in other tissues. This study provides a basis for a simple and efficient gene-therapy approach for patients with Fabry disease and is indicative of its potential for the treatment of other lysosomal storage disorders.