Panic disorder has an elevated prevalence in Parkinson's disease (PD). To explore the basis for this co-occurrence, the familial aggregation of panic disorder was examined in patients with PD. Probands and relatives of patients with PD and panic disorder (PD-PANIC; N=20, N=115) and control probands with PD and no active psychiatric illness (PD-NA; N=17, N=108) were interviewed by phone, using a structured interview to determine panic status. Lifetime prevalence of panic and "panic-like" disorders was higher in PD-PANIC than in PD-NA relatives. Panic and "panic-like" disorders are familial disorders in PD.