In a retrospective study of adults with severe community-acquired pneumonia (SCAP) admitted to the intensive care unit, 60 patients were identified from 25 hospitals within the 12-month study period. Thirty-two percent were aged less than 44 years and 65% less than 65. One-third were previously fit. Two or more of the following three features, respiratory rate greater than or equal to 30 min-1, diastolic blood pressure less than or equal to 60 mmHg and blood urea greater than 7 mmol l-1, were present in 72%. A pathogen was identified in 58% and five pathogens, Streptococcus pneumoniae, Haemophilus influenzae, Legionella pneumophila, Mycoplasma pneumoniae and Staphylococcus aureus accounted for 86% of these. Gram-negative enterobacteria were identified only once. Forty-eight percent reached the intensive care unit within 24 h of hospital admission, with respiratory failure or progressive exhaustion being the main reason for transfer. However, eight patients were only transferred following a cardio-respiratory arrest on the general ward. Eighty-eight percent received assisted ventilation which was given for a median of 8 days. A median of 4 (range 1-11) different antibiotics were given to each patient, with erythromycin and the penicillins prescribed most frequently. Aminoglycosides were given to 43% of patients, although Gram-negative enterobacteria were rarely found. Forty-eight percent died during the acute illness and a further 5% died shortly afterwards. Multi-organ failure was common with respiratory failure alone accounting for a minority of deaths. Forty-eight percent of deaths occurred within 1 week of hospital admission, but of 18 patients still receiving assisted ventilation at 14 days, 67% survived.(ABSTRACT TRUNCATED AT 250 WORDS)