Ten patients with Parkinson’s disease (Hoehn and Yahr stage 2.5-3) received ten, 45-minute, treatment sessions, five days a week, for two consecutive weeks. Robot-assisted arm training was performed with the Bi-Manu-Track (Reha-Stim, Berlin, Germany), which provides a computer-controlled, repetitive, bilateral, mirror-like practice of forearm pronation/supination and wrist extension/flexion. Patients were trained according to the following modalities: passive-passive (both arms moved by the machine) and active-active (both arms actively moving against resistance). The dominant upper limb was evaluated before and immediately after treatment as well as at two weeks of follow-up. Outcomes were the nine-hole peg test, the Fugl-Meyer assessment (upper limb section) and the Unified Parkinson’s Disease Rating Scale. After treatment, a significant improvement was found in the nine-hole peg test (P = 0.007) as well as in the upper limb section of the Fugl-Meyer assessment (P = 0.012). Findings were confirmed at the 2-week follow-up evaluation only for the nine-hole peg test (P = 0.007). No significant improvement was found in the Unified Parkinson’s Disease Rating Scale at both post-treatment and follow-up evaluations.