Purpose:The purpose of this study was to identify the factors influencing health-related quality of life (HRQOL) of patients with chronic obstructive pulmonary disease (COPD). Methods: A sample of 108 Patients diagnosed with COPD was recruited from outpatients, at a university hospital. Data were collected from February to April in 2016 using the St. George's Respiratory Questionnaire, the Hospital Anxiety-Depression Scale, and the COPD Self-efficacy scale. Results: The average score of HRQOL was 47.56 in patients with COPD. Results of the regression analysis showed that dyspnea phase (β=.34, p<.001) and presence or absence of oxygen (β=.20, p=.009), anxiety (β=.29, p<.001), FEV1 % predicted (β=-.15, p=.014) were statistically significant in patients' HRQOL. Conclusion: The research findings show that dyspnea phase and anxiety among psychological factors were the most powerful factors that explain the HRQOL of COPD patients when the demographic and disease characteristics were controlled. Identification of quality of life-related factors should be used to inform targeted interventions, in order to improve HRQOL and help patients' cope.