Oxidative stress plays an important role in the pathogenesis of Parkinson's disease (PD). In a population-based, case-control study we examined whether dietary intake of antioxidants and other oxidative compounds was associated with PD. Dietary intake was assessed by a semiquantitative food-frequency questionnaire in 110 PD case patients and 287 control subjects. A higher caloric intake was observed in patients with PD and did not vary with increasing duration of symptoms. Energy-adjusted fat intake was significantly higher among patients with PD than control subjects (p for trend = 0.007). Intake of protein (p for trend = 0.17) and carbohydrates (p for trend = 0.46) did not differ in patients and control subjects. Analyses of the primary sources of fat indicated that increasing intake of animal fats were strongly related to PD (odds ratio, 5.3; 95% confidence interval, 1.8-15.5; p for trend = 0.001). No significant differences were observed for intake of vitamins with antioxidant activity. An increase in the consumption of animal fats among patients with PD is consistent with the hypothesis that oxidative stress and lipid peroxidation are important in the pathogenesis of this disease. No effect of vitamins with antioxidant activity, either from food or supplements, was observed.