Recent success in delivering vision to a canine model of a severe, early-onset blinding disease, Leber congenital amaurosis (LCA) (Acland et al 2001) demonstrates that adeno-associated virus serotype 2 (AAV2) is capable of delivering a corrective gene to the target retinal cells. Results of these studies indicate long-term rescue of vision as assessed by psychophysical, behavioural and molecular biological studies. Preliminary results of studies in progress are described and the implications of these results with respect to developing human clinical trials for LCA and for other retinal degenerative diseases are discussed.