Fluorescein angiography was performed in nine members of families with Leber's disease. Serial studies were obtained in four men observed from asymptomatic to atrophic stages. Peripapillary microangiopathy was observed in six of nine asymptomatic eyes. Arteriovenous shunting occurred in the telangiectatic vascular bed. These changes remained stable in some eyes and progressed in others. In the acute stage, arteries and telangiectatic vessels were maximally dilated and flow was rapid. Angiography showed florid shunting in lower and upper vascular arcades and reduced filling of papillomacular capillaries. Vessels of the shunting vascular bed gradually narrowed irregularly. In the atrophic stage, disc vascularity diminished and arteriovenous circulation time increased markedly. Arterioles narrowed and peripapillary microangiopathy disappeared. These findings support our contention that Leber's disease is a hereditary vascular neuroretinopathy.