Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by airflow limitation that is not fully reversible. The main underlying cause of the disease is tobacco smoking, which destroys the patient’s bronchi and alveoli. COPD is a major public health problem in both developed and developing countries. There is much evidence to suggest that drug counseling may improve patient outcomes. The objective of this study was to compare the outcomes of drug counseling of COPD patients in experimental (received drug counseling) and control groups. The outcomes were knowledge about COPD, frequency of exacerbation, and quality of life. Patient knowledge was evaluated by a 10 item knowledge test about COPD, treatment and self-management. The frequency of the disease exacerbation was recorded. Patient quality of life was measured by the THAI version of the WHOQOL-BREF questionnaire which contains 26 items of five domains including physical, psychological, social relationship, environment, and quality of life overview. Knowledge about COPD, treatment and selfmanagement of the experimental group were significantly higher than the control group (p < 0.05). The frequency of the disease exacerbation in the experimental group was significantly less than the control group (p < 0.05). The overall of quality of life between two groups was not different. However, the experimental group had higher scores than the control group, in physical domain (p < 0.05) and quality of life overview domain (p < 0.05). The study showed that the experimental group had better outcomes than the control group in terms of knowledge about COPD, treatment and self-management, frequency of the disease exacerbation, and two domains of the qualities, physical domain and the quality of life overview domain.