We found an unusual form of macular dystrophy in three patients from two generations of the same family. The fundi of these patients appeared normal by ophthalmoscopy and fluorescein angiography, even in an older patient and in patients with poor visual acuity. Results of full-field electroretinograms were also normal in both cone and rod components. Focal macular electroretinograms were severely affected, however, indicating retinal impairment in the macular region. Results of Tübingen perimetry were consistent with electroretinographic findings. Since the condition was progressive, this disease is thought to be a hereditary macular dystrophy without visible fundus abnormality.