The mechanism of pathogenesis of idiopathic Parkinson's disease (PD) is unknown. In a study of 200 PD patients and 200 age- and sex-matched controls, Strang noted a marked and statistically significant higher incidence of ulcers (diagnosed by X-ray or surgery) in the PD patients compared to the controls (14% to 4%). These results have been discussed but never explained. Studies have shown increased concentrations of aluminum in the substantia nigra of PD patients compared to controls. Aluminum is thought to be a cellular toxin. Here I suggest that aluminum, and in particular aluminum-containing antacids may contribute to the pathogenesis of idiopathic PD.