Patients with chronic obstructive pulmonary disease (COPD) have an increased risk of death from causes other than COPD. A study was undertaken to identify the most common comorbid diseases and to assess prognostic role of comorbidity in COPD. A cohort of 406 COPD patients, mean (+/- SD) 64 +/- 9 years were evaluated. Age, sex, smoking history, FEV1, comorbid conditions were recorded. Follow-up was conducted by means of telephone calls. Logistic regression analysis was used to identify the independent predictors of death. The mean (+/- SD) FEV1 was 1.40 +/- 0.58 L. The most common comorbid diseases were hypertension (22%), coronary heart disease (8.9%), diabetes mellitus (7.4%), cancer (6.4%), heart failure (4.9%) and cerebrovascular disease (2%). The median follow-up was (+/- SD) 21 +/- 11 months. Twenty-four (5.9%) patients died during the follow-up period. Deaths from COPD were associated with FEV1 [RR 0.143 (95% CI 0.75-1.21)], heart failure (RR 0.177) and cancer (RR 0.064). In conclusion; while the most common comorbid diseases in COPD were hypertension, coronary heart disease and diabetes mellitus; FEV1, heart failure and cancer were associated factors with increased risk of death from COPD.