Dyspnoea measurements in chronic obstructive pulmonary disease (COPD) can be broadly divided into two categories: those that assess breathlessness during exercise, and those that assess breathlessness during daily activities. We investigated the relationships between dyspnoea at the end of exercise and during daily activities with clinical measurements and mortality in COPD patients. We examined 143 male outpatients with moderate to very severe COPD. The peak Borg score at the end of progressive cycle ergometry was used for the assessment of peak dyspnoea rating during exercise, and the Baseline Dyspnea Index (BDI) score was used for dyspnoea with activities of daily living. Relationships between these dyspnoea ratings with other clinical measurements of pulmonary function, exercise indices, health status and psychological status were then investigated. In addition, their relationship with the 5-year mortality of COPD patients was also analyzed to examine their predictive ability. Although the BDI score was significantly correlated with airflow limitation, diffusing capacity, exercise indices, health status and psychological status, the Borg score at the end of exercise had non-existent or only weak correlations with them. The BDI score was strongly significantly correlated with mortality, whereas the Borg score was not. Dyspnoea during daily activities was more significantly correlated with objective and subjective measurements of COPD than dyspnoea at the end of exercise. In addition, the former was more predictive of mortality. Dyspnoea with activities of daily living is considered to be a better measurement for evaluating the disease severity of COPD than peak dyspnoea during exercise.