A discharge register maintained by the National Research and Development Center for Welfare and Health was employed to study the use of hospital services, attributable to chronic obstructive pulmonary disease (COPD), in Finland. From a total population of 5 million COPD caused 113,016 hospital treatment periods during 1983-92 of persons aged 35 years or over. In men the need of hospital treatment for COPD started to rise sharply after the age of 50. Men aged 73 had the highest amount of admissions (3962 admissions per 10-year period). Women aged 68 had the highest amount of admissions (802 admissions per 10-year period). The highest admission rate per 1000 inhabitants was found for men at the age of 82 (37.0 admissions per 1000 population/ year) and for women at the age of 77 (3.8 admissions per 1000 population/year). During the 10-year period a total of 27,008 new COPD patients aged 35 or over received hospital care. The highest number of new admissions occurred among both sexes at the age of 71 (750 admissions per 10-year period in men and 233 admissions per 10-year period in women). This means that most of admissions are due to elderly COPD patients seeking treatment repeatedly. As the populations in the developed countries are ageing, the significance of COPD for the health care system is growing.