Purpose: The aim of this study was to identify predictors of influencing on the physical function and life satisfaction in patients who underwent knee replacement arthroplasty. Methods: A convenience sampling of 70 patients who were hospitalized for knee replacement arthroplasty was taken from a university hospital. The instruments for the study were the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index, Life Satisfaction, Scale and the Geriatric Depression Scale. The exercise capacity was measured. Data were analyzed using t-test, one-way ANOVA, Pearson's correlation coefficient, repeated measures ANOVA and multiple regression with PASW version 18.0. Results: The WOMAC index (F=48.28, p<.001) and the life satisfaction (F=12.45, p<.001) showed a significant change over time, with measurements before surgery, at 1 month and 3 months after surgery. The predictors of the WOMAC index at 3 months after surgery were leg muscle strength at discharge(β=.40) and life satisfaction at 1 month after surgery (β=.75). Life satisfaction at 3 months after surgery accurately predicted 44% of the WOMAC index at 3 months after surgery (β=-.48) and depression before surgery (β=-.35). Conclusion: The findings indicate that reducing depressive mood and strengthening leg muscles will improve patients' physical function and life satisfaction after knee replacement arthroplasty.