We examined the potential sex-related differences in levodopa pharmacokinetics and their relation with the presence of dyskinesias in a group of 115 patients (67 men, 49 women) with Parkinson's disease. The patients were given a standard oral dose of levodopa plus benserazide (100/25 mg). The area under the levodopa plasma concentration time curve, corrected for the levodopa test dose (in mg/kg body weight), (AUC(w)) was significantly higher in women than in men, with a reduced oral clearance. No difference in the proportion of men and women experiencing dyskinesias was observed.