We measured the severity of left spatial neglect in 29 patients, 2 to 4 weeks after right cerebral infarction. The severity of neglect increased with both the size of the lesion and the degree of premorbid diffuse cortical atrophy. Recovery over 3 to 5 months from an initially moderate to severe neglect was less complete in patients with cortical atrophy. The importance of lesion size shows that spared areas of the right hemisphere limit the severity and duration of left neglect. The importance of premorbid atrophy suggests that the integrity of the left hemisphere is also essential.