Aims: To investigate joint functioning and the quality of life (QOL) before and after total knee and total hip replacement and the factors that influence the QOL. Methods: A longitudinal study was conducted between August 2015 and January 2017. A questionnaire composed of the EQ-5D, Oxford Hip Score, and Oxford Knee Score was used to collect data before surgery and 6 weeks, 3 months, and 6 months after surgery. Results: A repeated-measures analysis of variance revealed significant differences in the EQ-5D utility index between the preoperative and all 3 postoperative periods (F = 124.195, P <.05). There were significant differences in knee functioning (F = 133.859, P <.05) and hip functioning (F = 34.717, P <.05) between the preoperative and all 3 postoperative periods. The EQ-5D utility index was significantly higher among patients undergoing total knee replacement than those undergoing total hip replacement (F = 15.490, P <.05) and higher among female than male patients (F = 7.613, P <.05). A positive correlation between the QOL and the perceived convenience of living at home was observed (P <.05). Conclusions: The findings are expected to inform patient education for patients undergoing arthroplasty surgery.