In Parkinson's disease (PD) the urinary dysfunction manifests primarily with symptoms of overactive bladder (OAB). The OAB questionnaire (OAB-q) is a measure designed to assess the impact of OAB symptoms on health-related quality of life. In this study, we quantified the urinary symptoms in a large cohort of PD patients by using the OAB-q short form. Possible correlations between the OAB-q and clinical features were tested. Three hundred and two PD patients were enrolled in the study. Correlations between the OAB-q and sex, age, Unified Parkinson's Disease Rating Scale part III (UPDRS-III), Hoehn-Yahr (H-Y) staging, disease duration, and treatment were analyzed. Data were compared with a large cohort of 303 age-matched healthy subjects. The OAB-q yielded significantly higher scores in PD patients than in healthy subjects. In the group of PD patients, all the variables tested were similar between men and women. Pearson's coefficient showed a significant correlation between mean age, disease duration, mean OAB-q scores, UPDRS-III scores, and H-Y staging. A multiple linear regression analysis showed that OAB-q values were significantly influenced by age and UPDRS-III. No statistical correlations were found between OAB-q scores and drug therapy or the equivalent levodopa dose, whilst the items relating to the nocturia symptoms were significantly associated with the equivalent levodopa dose. Our findings suggest that bladder dysfunction assessed by OAB-q mainly correlates with UPDRS-III scores for severity of motor impairment, possibly reflecting the known role of the decline in nigrostriatal dopaminergic function in bladder dysfunction associated with PD and patients' age. Our study also suggests that the OAB-q is a simple, easily administered test that can objectively evaluate bladder function in patients with PD.