The adult respiratory distress syndrome (ARDS) is a syndrome of diffuse lung injury with a high mortality rate. We evaluated retrospectively 35 adult patients with ARDS. Their overall mortality rate was 69% and was related to their age (32 +/- 14 yr in survivors and 54 +/- 15 yr in nonsurvivors; p less than .001) and to the number of complications during their illness (1.4 complications in survivors, 2.6 in nonsurvivors; p less than .005). The ARDS patients, due to an infectious etiology, incurred a 75% mortality rate, while those with a noninfectious etiology of ARDS had a 55% mortality rate (nonsignificant). Neither a simplified acute physiology score nor a respiratory failure severity index was significantly different between survivors and nonsurvivors on admission. The mean PEEP level on admission in survivors was 8.1 +/- 4.6 cm H2O and in nonsurvivors 3.7 +/- 3.9 cm H2O (p less than .025). We conclude that the age of the patients and superimposed multiple system organ failure are probably related with the still high mortality rate of this syndrome.