The authors describe a multicenter, randomized, blinded, placebo-controlled trial, comparing sucralfate with the H₂-receptor antagonist ranitidine for the prevention of upper GI bleeding in 1,200 patients who required mechanical ventilation.  Patients receiving ranitidine had a significantly lower rate of clinically important GI bleeding than those treated with sucralfate.  There were no significant differences in the rates of ventilator-associated pneumonia, the duration of the stay in the ICU, or mortality.