• Amblyopia can result from strabismus, anisometropia, media opacities, and congenital disorders such as nystagmus. Complicated forms of ptosis (ie, associated with neurofibroma or hemangioma) are also known to cause amblyopia. A previously unconfirmed cause of amblyopia is uncomplicated ptosis. We carefully examined 123 consecutive surgical ptosis patients with uncomplicated congenital or early acquired ptosis. Twenty-five cases of amblyopia (20%) were seen. Four cases (3.2%) were thought to be caused by the ptosis. In two of these cases (1.6%), the amblyopia was directly attributed to the ptosis. In one of the remaining two cases, exotropia and amblyopia developed on the ptotic side while the patient was being observed for the ptosis. In another patient, a progressively increasing cylindrical refractive error and amblyopia developed, which were attributed to the ptosis. We recommend careful evaluation of cases of congenital ptosis for the detection and treatment of amblyopia.