Objective: To describe the pathologic changes that caused a left homonymous hemianopsia in a patient with dementia with Lewy bodies. Design: Report of a case and postmortem studies. Main Outcome and Results: A 66- year-old woman experienced parkinsonism and left homonymous hemianopsia early in the course of a rapidly progressive dementia that culminated in death only 21 months after the onset of her symptoms. Postmortem examination revealed pathologic features consistent with the diagnosis of dementia with Lewy bodies. The only apparent explanation for her visual field deficit was a disproportionately large number of neurofibrillary tangles in the right striate, peristriate, and inferotemporal cortices. Conclusion: A clinically obvious homonymous hemianopsia can result from the occipital and inferotemporal cortical degeneration in dementia with Lewy bodies.