We examined the pupils of 55 amblyopic subjects to determine whether a pupillary defect could be detected in the amblyopic eye. We found relative afferent pupillary defects in 45 of the subjects; these defects were equal to or larger than 0.3 log unit (that is, easily visible) in 29 subjects. The pupillary defect was always in the amblyopic eye, but it could not be correlated with the severity or the cause of the amblyopia, with visual-evoked potential abnormalities, or with color vision defects.