The purpose of this study was to compare the short-term changes in quality of life for patients younger than 80 years with those 80 years and older undergoing total knee arthroplasty (TKA). It was hypothesized that patients 80 years and older had a similar quality of life after TKA compared with those younger than 80 years. All consecutive patients undergoing primary TKA were enrolled in this prospective, comparative, prognostic (level I evidence) study and were stratified into 2 groups based on their age (younger than 80 years and 80 years and older). Data on quality of life assessed using the Short Form 36 health survey were obtained preoperatively and 1 year postoperatively (short-term follow-up) and were compared between groups. A total of 328 (83.89%) patients younger than 80 years (mean age, 70.7 years) and 63 (16.11%) patients 80 years and older (mean age, 82.1 years) were included. No significant differences in preoperative quality of life were observed between groups. Postoperative physical function, vitality, social function, and physical component summary were lower in patients 80 years and older. Older patients had a lower difference between pre- and postoperative values in Short Form 36 physical function and role-emotional scores. Patients 80 years and older had a similar improvement in quality of life 1 year after TKA compared with patients younger than 80 years. Therefore, changes in quality of life justify TKA as a treatment option for elderly patients with end-stage knee osteoarthritis.