Many lesions along the visual pathway from the retina to the occipital cortex can cause a horizontal hemianopia. The anatomy of the visual pathway is reviewed in an attempt to clarify how and where this visual field defect develops. A case is presented in which two ischemic occipital infarcts caused a bilateral inferior horizontal hemianopia and complex visual hallucinations. Previous cases of occipital lesions resulting in an altitudinal hemianopia are reviewed.