Depression is common in COPD patients. Around 40% are affected by severe depressive symptoms or clinical depression. It is not easy to diagnose depression in COPD patients because of overlapping symptoms between COPD and depression. However, the six-item Hamilton Depression Subscale appears to be a useful screening tool. Quality of life is strongly impaired in COPD patients and patients' quality of life emerges to be more correlated with the presence of depressive symptoms than with the severity of COPD. Nortriptyline and imipramine are effective in the treatment of depression, but little is known about the usefulness of newer antidepressants. In patients with milder depression, pulmonary rehabilitation as well as cognitive-behavioral therapy are effective. Little is known about the long-term outcome in COPD patients with co-morbid depression. Preliminary data suggest that co-morbid depression may be an independent protector for mortality.