The purpose of this study was to identify the technical difficulties, complications, and long-term outcome of total knee arthroplasty in patients with Paget's disease. Twenty consecutive patients (21 knees) with Paget's disease at the knee who underwent primary total knee arthroplasty were retrospectively reviewed. All arthroplasties employed cemented condylar implants. Two patients died at less than 2 years and one was lost to follow-up; the remaining 17 (18 knees) were followed for an average of 9 years. Mean Knee Society scores for pain and function improved from 41 and 36 points preoperatively to 87 and 67 points, respectively, postoperatively. One patient underwent femoral revision for aseptic loosening at 10 years. None developed substantial heterotopic ossifications or deep infection. Total knee arthroplasty in patients with Paget's disease can provide good clinical results with low revision rate and good implant durability, despite technical challenges.