In 20 patients idiopathic focal subretinal neovascularization was characterized by a solitary focus of subretinal neovascularization at or near the fovea, associated with serous or hemorrhagic detachment of the overlying and adjacent sensory retina, or both. Although the lesions resembled the neovascular membrane seen in the presumed ocular histoplasmosis syndrome, none of the other associated characteristic ophthalmoscopic findings, considered essential to make the latter diagnosis, were apparent. In this group of patients, the incidence of positive histoplasmin skin tests was no greater than in the general population. Of the 20 patients, two had bilateral disease. In no case were there any other lesions of any kind in the afflicted or the opposite eye. The disease is self-limited over a variable period of time, but may result in extensive scarring with loss of central vision.