Visual hallucinations (VH) are a common feature of Parkinson disease (PD); however, the cognitive profile preceding the onset of VH has not yet been established. The present study investigated longitudinal neuropsychological performance of patients with PD who developed VH during follow-up compared to a group who did not develop VH. The patient groups were matched for demographic and disease severity variables at their baseline assessments. Patients who developed VH displayed impaired performance at baseline on measures of psychomotor speed, executive functioning, reaction time, and attention compared to patients who did not develop VH. These results demonstrate a profile of cognitive deficits specific to patients with PD at risk of developing VH and implicate attentional dysfunction in the early pathogenesis of VH.