Visual search and line orientation discrimination was studied in 67 brain-damaged and 15 control subjects, with the aim of demonstrating that hemi-inattention follows both left- and right-hemisphere damage even when confined to the frontal lobe. Both anterior and posterior lesions of either hemisphere caused inattention to the side contralateral to the lesion, this asymmetry being pronounced at the onset of search, especially in patients with anterior lesions. Hemi-inattention was associated with the overall inefficiency of line orientation discrimination and exploration as well as simple verbal performance in right-hemisphere-damaged patients, but tended to dissociate from these deficits in left hemisphere-damaged patients. Brain-damaged patients were inferior to the control subjects, and women inferior to men in the overall efficiency of exploration, but only women with right posterior lesions had a deficit in line orientation discrimination.