Introduction The knee in Parkinson's disease (PD) patients is a problematic joint due to pain, stiffness and gait instability. The aim of this study is to evaluate the functional outcome and degree of pain relief achieved after total knee arthroplasty (TKA) in PD patients. Materials and methods This is a retrospective review of 26 PD patients (32 knees) with osteoarthritis who underwent a TKA between 1994 and 2013. Comorbidities, anesthetic procedures and complications were recorded. Patient functional status was assessed with the Knee Society Function Score (KFS) and the Knee Society Score (KSS). PD stage was classified with the Hoehn and Yahr Scale. Results The mean follow-up was 3.5 years (range 2-9). The mean age was 71 years (range 61-83) with a mean time since PD diagnosis of 11.8 years (range 4-24). PD severity on the Hoehn and Yahr Scale was 1.5 points before surgery and 2 points postoperatively. Pain on the visual analogic scale improved from 8 points preoperatively to 5 points at 1-year follow-up; function improved from 32 (range 20-45) to 71 (range 50-81) and from 34 (range 28-52) to 59 (range 25-76) on the KSS and KFS, respectively. The mean postoperative hospital stay was 9.8 days (range 5-21). Confusion and flexion contracture were the most frequent perioperative complications. Conclusion TKA successfully provided pain relief in PD patients. However, the functional outcome is related to disease progression and, therefore, variable. Perioperative complications are difficult to avoid and manage.