Purpose: This study aims to investigate the relationships between knowledge on advance directive, attitudes towards the withdrawal of life-sustaining treatment and quality of life among hemodialysis patients. Methods: A descriptive correlational study was conducted with 103 hemodialysis patients. Data were collected using a structured questionnaire from May to September of 2016, and analysed by using descriptive statistics, t-test, ANOVA and Pearson correlation coefficient. Results: The participants' knowledge level on advance directive was 5.47±2.08 out of 9, the attitudes towards the withdrawal of life-sustaining treatment was 3.22±0.49 out of 5, and the quality of life was 3.35±0.92 out of 6. The knowledge on advance directive was positively correlated with attitudes towards the withdrawal of life-sustaining treatment (r=.21, p=.037) and quality of life (r=.21, p=.036). Conclusion: According to the results of this study, the level of knowledge on advance directive is preferred to improve the quality of life of hemodialysis patients. It is needed to support and maintain ongoing education opportunities in order to improve the level of knowledge on advance directive among patients undergoing hemodialysis.