Patients admitted to intensive care units frequently develop stress ulcers, erosive gastritis and complications such as upper gastrointestinal bleeding. Stress-related upper gastrointestinal bleeding (UGIB) has been of particular concern to many practitioners working in intensive care units and has led to the treatment of most if not all patients admitted to these units with antacids, H2 receptor antagonists or sucralfate in order to protect the gastric mucosa. It is considered that the 3 aforementioned medications are effective in decreasing the overall incidence of UGIB, but it has not been demonstrated that they are efficacious in reducing the incidence of clinically significant UGIB, ie cases that are complicated by anemia, hemorrhagic shock, or death. In addition, the cost and complications resulting from prophylaxis should be taken into consideration, which raises further questions about the systematic use of these agents. This article reviews the current literature on this subject; the authors propose a conservative use of prophylaxis, and that these agents be prescribed in a selective manner to the patients at the greatest risk of developing UGIB.