We have investigated the prevalence of gastrointestinal (GI) symptoms in 98 individuals with Parkinson's disease (PD) and in a control group of 50. Seventy-nine of those with PD were being treated with dopaminergic medications and 19 were untreated. Those symptoms occurring more frequently in PD patients than in controls included abnormal salivation, dysphagia, nausea, constipation, and defecatory dysfunction. Except for defecatory dysfunction, symptoms did not correlate with treatment but instead correlated with disease severity. This suggests that the GI symptoms of PD reflect direct involvement in the GI tract by the primary disease process.