We examined the relationships among dyspnea ratings in daily life, the physiologic state, and anxiety and depression of fifty-two patients with chronic obstructive disease (COPD) during long-term domiciliary oxygen therapy (LTOT). Clinical ratings of dyspnea were assessed by the visual-analog scale (VAS) during eight types of basic behavior in indoor daily life. Analysis of the physiologic state included forced expiratory volume in 1 second (FEV1.0), and arterial blood gas (PaO2, PaCO2) at rest while breathing room air. The hospital anxiety and depression (HAD) scale, which consists of 14 questions, was used to assess the degree of anxiety (HAD-A) and depression (HAD-D). The mean age of the patients was 69.5 +/- 10.8 year (SD), and the duration of LTOT was 944 +/- 739 days. The mean values were 0.77 +/- 0.45 L for FEV1.0, 57.7 +/- 7.4 Torr for PaO2, and 47.4 +/- 8.1 Torr for PaCO2. FEV1.0 was correlated with PaCO2(r = -0.548, p < 0.0001), but it was not correlated with PaO2. High correlation was noted between HAD-A and HAD-D (r = 0.693, P < 0.0001), whereas correlation was not noted between HAD and the physiologic state. VAS was significantly correlated with FEV1.0 (r = 0.320, p < 0.05), as well as with HAD-A (r = 0.358, p < 0.01) and HAD-D (r = 0.444, p < 0.01). Dyspnea ratings were found to be influenced by anxiety and the depression state, and also by the degree of flow limitation in patients with COPD during LTOT. In contrast, the physiologic state scarcely influenced the anxiety and depression state. Thus, psychotherapy may play an important role in the reduction of dyspnea sensation, which is an important determinant of quality of life.