Introduction: Approximately 88% of men and 79% of women with Parkinson's disease (PD) identify an informal caregiver. Although caregivers can play a key role in supporting patients, little is known about how and whether PD patients with and without caregivers differ in terms of physical, cognitive, and mood outcomes. This study explored whether caregiver presence was associated with variations in patient presentation and outcomes in a palliative PD and atypical PD population.