The paper describes the comparatively benign nature of granular corneal dystrophy Groenouw type I and the results of treatment of the disease. 71 patients with a classic clinical appearance comprised the largest pedigree in medical literature. The disorder was confined to the eyes only. Visual acuity was close to normal in children; the children had small, superficial, corneal opacities, often arranged in lines, and for the most part with a smooth exterior surface when examined with Javal keratometry. In adult patients visual acuity was around 0.5, the exterior surface uneven, the corneal opacities larger, and distributed superficially as well as deeper in the corneal stroma. In elderly patients visual acuity was between 0.5 and 0.1 and they all had additional cataract. Fourteen patients were treated with corneal grafting during the past 15 years and all grafts remained clear.