Dystrophy of the basement membrane of the corneal epithelium is an autosomal-dominant disease. Three distinct forms of opacity occur, either in isolation or in combination with one another. These are (1) dotlike opacities, (2) maplike opacities and (3) fingerprint lines. The present paper describes a family in which 6 members show only the characteristic signs of superficial maplike corneal opacities. There have been no recurrent corneal erosions. In addition, 7 "isolated cases" are described in which both the pure and combined forms of opacity have been observed. The dotlike opacities are demonstrable only when maplike alterations are also present. The patholomechanism leading to these dotlike changes cannot be explained by aberrance of the basement membrane alone. Cases of the three forms of opacity which may occur as secondary phenomena have to be distinguished from the dystrophic form.