Reducing tidal volumes administered to patients with acute lung injury is the only intervention reported to decrease mortality resulting from this life-threatening condition. Whereas many medical advances are slowly brought into practice, clinicians in teaching hospitals are often assumed to be early adopters of new medical advances. Our objective was to examine trends in the ventilatory prescription for 398 patients with acute lung injury treated in three teaching hospitals from 1994 to 2001. There was no change in tidal volumes until mid to late 1998, when volumes started to slowly decline at the rate of 48.0 (95% confidence interval, 21.0 to 74.4) ml/year. In the 2 years after the results were released from a large trial that demonstrated the superiority of 6 ml/kg tidal volume therapy over 12 ml/kg, clinicians prescribed tidal volumes of 651 +/- 128 ml or 10.1 +/- 1.9 ml/kg. Tidal volumes after intubation were minimally reduced over the subsequent 2 days of mechanical ventilation (mean reduction, 33 ml). Hospital category, male sex, and disease onset before May 1999 were associated with higher volumes whereas lung injury severity was inversely associated. We conclude that clinicians practicing at these teaching hospitals have not rapidly adopted low tidal volume ventilation that may reduce mortality.