α-Synuclein (α-Syn), a protein synthesized by neurons, as the major protein component of Lewy body inclusions, undoubtedly has a prominent role in the pathogenesis of Parkinson's Disease (PD). In an attempt to enable pre-symptomatic and definitive diagnosis, numerous attempts have been made to align assayed total α-Syn levels in serum (where there is a native presence) to PD disease status. Results have been conflicting. The status of circulating and potentially neuroprotective α-Syn autoantibodies in PD subjects is also unclear. In previous work we demonstrated that electrochemically assayed autoantibody levels were higher in PD patients compared to controls and, significantly, noted that this differentiation was most marked early in disease. Herein we report a robust (coefficient of variation 3.0%) single step and label free analysis of 90 subjects, including 60 PD patients, with a mean disease duration of 1.4 years and 29 control subjects. In this cross sectional cohort we observe a statistically significant (p < 0.05; Mann–Whitney U test) difference in autoantibody levels in PD patients versus controls, although there was no resolved scaling with symptomatic disease stage (p > 0.05; Kruskal–Wallis test).