We conducted this study to review the clinical and radiographic outcomes of patients 80 years of age or older who underwent total knee arthroplasty (TKA). We identified clinical results in 60 patients (66 knees) who had a mean age of 84 years (range, 80 to 95 years) and who underwent TKA. These were compared with a non-age-matched group of 63 patients (66 knees) who had a mean age of 69 years (range, 60 to 79 years). Four patients were lost to follow-up. After a mean 43-month follow-up (range, 24 to 117 months), Knee Society pain and function scores for the study group improved from 53 points (range, 25 to 70 points) and 53 points (range, 40 to 70 points), respectively, to 94 points (range, 75 to 100 points) and 87 points (range, 45 to 100 points). There were no implant failures, 2 surgical complications, and 13 medical complications. In the matching group, there were four surgical complications (two required revision) and two medical complications. There were no radiographic failures or progressive radiolucencies. Although the incidence of medical complications in the perioperative period may be higher, TKA is a safe and effective treatment for refractory joint pain in patients over 80 years of age.