Those patients with chronic obstructive pulmonary disease (COPD) who require hospital treatment are severely ill. We have studied the survival and cause of death among COPD patients in Finland after their first admission to hospital due to COPD. COPD-related treatment periods in all hospitals during 1972-1992 were collected from the national discharge register, and a subgroup was defined consisting of 2,237 patients aged 65-69 years who had their first admission during 1986-1990. Survival and causes of death were analysed for this group using the data contained in the national mortality statistics. The mortality data were recorded up to the end of 1993. By the end of 1993, 1,070 persons (48%) in the study group had died. The median survival time was 5.71 years (95% CI 5.27-6.15). Female COPD patients had a more favourable prognosis than males. COPD had been certified as the main cause of death for 33.3% of the women and 29.4% of the men. The proportion of COPD as main cause of death increased with an increasing number of treatment periods prior to death. In conclusion, the first hospital admission for COPD indicates a poor prognosis. A high incidence of pulmonary cancer contributes to the poor outcome in the case of men. COPD is obviously underrated on death certificates as the cause of death among COPD patients.