Disease progression, support required, prognostic indicators and survival in hospital and after discharge were studied in 53 patients with community acquired infections who required admission to the intensive care unit from the Department of Infectious Diseases between January, 1985 and August, 1991. The median age was 37 years and over two-thirds of patients were previously fully fit; 38 per cent of patients required intensive care within 6 hours of admission with rapidly progressive disease. Both APACHE II scores and number of organ systems failed were good indicators of prognosis: mortality was 85 per cent in those with three or more organ failures and 86 per cent in those with APACHE II scores of > or = 25. No deaths were observed in those with scores of < 10. Some organ failures (cardiovascular, renal and respiratory) occurred more frequently in those who died. Mechanical ventilation was required by 60 per cent of patients, inotropic drugs by 42 per cent and renal dialysis by 17 per cent. Mortality in hospital was 25 per cent with no further deaths at 6 months to 2 years. As a group these patients were young and previously fit. Deterioration was rapid, necessitating admission to the intensive care unit at short notice. Our results highlight the importance of having intensive care facilities in close proximity to infectious disease units. In contrast to many other groups of patients admitted to the intensive care unit, the overall outlook for patients with community acquired life-threatening infections is good, and long-term monitoring suggests that these patients remain well once recovery has occurred.