This article explores the relation between spatial attention and feature integration by examining the occurrence of illusory conjunctions in a parietal patient with a known deficit of spatial attention. The patient was tested in 12 separate sessions. When the patient had to focus her attention in the middle of the visual field she committed a much larger number of illusory conjunctions on the side contralaterai to her lesion than on the side ipsilateral to her lesion. When the patient did not have to focus her attention in the middle of the visual field, however, the number of illusory conjunctions was dramatically reduced. These results indicate that the spatial attention mechanism plays a central role in feature integration.