Many retinal disorders present during infancy with nystagmus, decreased vision, and normal-appearing fundi, but an abnormal ERG. The most common of these disorders are Leber's congenital amaurosis, achromatopsia, and congenital stationary night-blindness. Other disorders with similar ocular manifestations may be associated with a variety of life-threatening systemic abnormalities. This review describes the clinical, electrophysiological, and laboratory findings that can be used to distinguish among these conditions.