BACKGROUND: Previous studies have implicated traumatic brain injury (TBI) as a risk factor for Parkinson disease (PD). However, the incidence risk of new-onset TBI among patients with PD is not well established. This study investigated the contribution of PD to new-onset TBI associations. METHODS: The study selected 6076 patients with PD and using 1:2 propensity score matching 12,152 general population cohorts in a longitudinal population database in Taiwan. The Cox proportional hazard regression model was used to estimate the hazard ratio of TBI adjusted with the potential confounding factors. RESULTS: The incidence of TBI in patients with PD (2.57%) and compared cohorts (1.81%) was significantly different (P = 0.0007). Patients with PD had a higher risk of TBI (hazard ratio, 1.63; 95% confidence interval, 1.32-2.01) compared with the general population. Patients with PD with TBI incidence had a higher Charlson Comorbidity Index than did the general population with TBI (P < 0.0001). Fall is the major cause of TBI in patients with PD. CONCLUSIONS: This study shows that patients with PD have a high risk of TBI, and the major cause of TBI in patients with PD is fall.