We investigated serum levels of interleukin (IL)-2, IL-10, IL-6, IL-4, TNFalpha, INFgamma in 7 patients with atypical parkinsonism (AP), 31 idiopathic PD (iPD) patients, 17 idiopathic PD with cardiovascular risk factor (iPD-CVRF) patients, and 20 age-matched controls (healthy, non-parkinsonian patients). Cytokine concentrations were measured using the Becton Dickinson (BD) human Th1/Th2 Cytokine kit II with a flow cytometry system. The concentrations of IL-2, IL-10, IL-4, IL-6, TNFalpha, and INFgamma were detectable in the serum from all groups, including the control. Increased serum IL-2, IL-10, IL-4, IL-6, TNFalpha, and INFgamma concentrations were found in all groups of parkinsonian patients, as compared to the control group. The highest elevations of serum IL-2, IL-4, IL-6, TNFalpha, and INFgamma concentrations were observed in AP patients, as compared to the iPD and iPD-CVRF groups. However, the serum IL-6 concentration was higher in the iPD-CVRF group than in the iPD group. The IL-10 level was significantly higher in all groups of PD patients relative to the control group, but was the lowest in the serum from the AP patients. Moreover, the serum levels of lipid peroxidation products were enhanced 2.1- and 1.5-fold in AP and both iPD groups, respectively. These results argue in favor of the involvement of immunological events in the process of neurodegeneration in AP and PD.