The objective of this study is to evaluate pursuit ocular movements (POM) by using a vision-based non-intrusive eye tracker, in patients with suspected Parkinson's disease (PD), before and after L: -Dopa administration. We studied ten patients with suspected diagnosis of idiopathic PD. We compared POM values to those of a group of normal controls (NC), and evaluated them before and after L: -Dopa administration. Unified Parkinson's Disease Rating Scale (UPDRS) motor subscores improved significantly (p = 0.001). At baseline, values of POM were lower in suspected PD patients than in NC (p = 0.01). One hour after L: -Dopa administration, POM values correlated with UPDRS motor subscore (p = 0.01). We used a recent method, a new vision-based non-intrusive eye tracker, previously described, which can be proposed as a possible tool for supporting the diagnosis of PD in association with levodopa test, as an add-on to the UPDRS score.