The aim of this investigation was to describe the use of hospital services among the Finnish working-age population aged 15 to 64 years on account of pneumonia. The study was based on nationwide hospital discharge records maintained by the National Research and Development Centre for Welfare and Health. Pneumonia caused 63,414 periods of hospital treatment and a total of 568,861 hospitalization days among working-age people in Finland from 1984 to 1993. The mean annual age-specific rate of pneumonia-related hospital treatment periods per 1000 persons among men was 2.67 (SD 0.17) and among women 1.10 (SD 0.08). The men had more treatment periods than the women in every 5-year age group, the greatest difference being in the youngest age groups and in the oldest ones. In men the mean annual rate of treatment periods increased rapidly after the age of 40 years (from 1.54 per 1000 persons in age group 40-45 years to 7.86 per 1000 in age group 60-64 years). In women the increase in corresponding age groups was more moderate (from 0.77 to 3.19). The increasing number of pneumonia-related hospital treatment periods after the age of 40 is facing the challenge for the occupational health care in the future.