In a cohort study covering whole Finland, the incidence of acute respiratory failure was higher than in previous international studies. The number of patients fulfilling the diagnostic criteria for acute lung injury and acute respiratory failure remained, however, smaller than that reported in international comparative data. The 90-day mortality was 31% and one-year mortality 35%. Recommended airway pressure levels were followed in ventilatory support treatment, but tidal volumes were larger than those in recent therapeutic trials. Patients outcome could probably be further improved by centralizing intensive care services.