A case of juvenile idiopathic sex-linked retinoschisis in a six-month-old child was followed for seven years. The familiar occurrence in males was in agreement with the sex-linked inheritance. The appearance at an early age in the left eye confirmed the congenital nature of the disease and the possibility that the ophthalmoscopic features might be present at birth, at least monocularly. In the right eye the ophthalmoscopial normaility of the vitreous as well as the early and severe abnormality of the electroretinographic findings (normal "a" wave, microvolted "b" photopic wave, extinct "b" scotopic wave and presence of only the first wavelet of the oscillatory potentials) at the initial stage of maculopathy induced the author to suppose that there might be primarily a tapeto-retinal heredodegeneration and that the pseudocystic degeneration of the inner layers could be a secondary manifestation of the disease.