BACKGROUND: Constipation is one of most frequent non-motor symptoms of Parkinson's disease (PD) and it may precede the clinical diagnosis of PD by years, with negative effects on quality of life. In contrast to motor features, levodopa is ineffective and possibly detrimental on constipation. Treatment of constipation in PD is non-specific and frequently unsuccessful. Stemming from a clinical observation of unexpected relief of bothersome constipation, abdominal bloating and pain after treatment with the beta-blocker carvedilol in one patient, we have evaluated the association between the use of beta-blockers and the presence of constipation in a large, unselected PD cohort. METHODS: Retrospective review of the medical records of every patient with a diagnosis of PD seen in the Movement Disorders clinic at Cedars-Sinai Medical Center from October 2010 to April 2014. RESULTS: 341 medical records with a primary diagnosis of PD were reviewed, 336 of which contained information about constipation. Overall, 205/336 patients (61%) reported constipation. Among the 66 subjects treated with beta-blockers at the time of the encounter of record, only 28 (42.4%) reported constipation. By comparison, among the 270 subjects not treated with beta-blockers, 177 (65.5%) had constipation (χ(2) test p value = 0.001). Multivariate logistic analysis showed an odds ratio (OR) of 0.293 for beta-blockers (95% C.I. 0.161-0.535, p = 0.0001), 2.287 for levodopa (95% C.I. 1.271-4.117, p = 0.006) and 1.805 for dopamine agonists (95% C.I. 1.039-3.136, p = 0.036). CONCLUSIONS: Beta-blockers are associated with a lower risk of constipation, while dopaminergic treatments appear to increase risk of constipation.