After a brain injury, whether traumatic or caused by a stroke, perceptual impairments are common. They are, however, only seldom revealed by a routine physical examination. In this article, the many manifestations of perceptual impairment and tests for perceptual function are briefly presented. It appears that perceptual deficits contribute largely to reduced self-care ability in patients with brain lesions. An effective training program for perceptual deficits remains to be developed.