BACKGROUND Bacterial infections are a frequent complication in patients with cirrhosis and gastrointestinal bleeding. Antibiotic prophylaxis seems to decrease the incidence of bacterial infections. Oral antibiotics, active against enteric bacteria, have been most often used as antibiotic prophylaxis in cirrhotic patients with gastrointestinal bleeding. OBJECTIVE This review aims to evaluate the effects of antibiotic prophylaxis in the prevention of bacterial infections in cirrhotic patients with gastrointestinal bleeding. METHODS Electronic searches on The Cochrane Hepato-Biliary Group Controlled Trials Register (May 2001), The Cochrane Library (Issue 2, 2001), EMBASE (1980-2001), and MEDLINE (1966-2001); handsearching the references of all identified studies; contacting the first author of each included trial. METHODS Randomised clinical trials comparing different types of antibiotic prophylaxis with placebo, no intervention, or another antibiotic to prevent bacterial infections in cirrhotic patients with gastrointestinal bleeding. METHODS Two reviewers independently appraised the quality of each trial and extracted the data from the included trials. Relative risks (RR) or average differences, with their 95% confidence intervals (CI) were estimated. The reviewers assumed an intention to treat basis for the outcome measures. RESULTS Eight trials evaluated the effects of antibiotic prophylaxis compared with placebo or no antibiotic prophylaxis in 864 patients. A significant beneficial effect on decreasing mortality (RR 0.73, 95% CI 0.55 to 0.95) and the incidence of bacterial infections (RR 0.40, 95% CI 0.32 to 0.51) was observed. No serious adverse events were reported. The trials showed no significant heterogeneity. Three additional trials evaluated the effects of antibiotics compared with a different regimen of antibiotics in 503 patients. Data could not be combined as each trial used different interventions. None of the examined antibiotic regimens was superior to the control regimen regarding mortality or the incidence of bacterial infections. CONCLUSIONS Antibiotic prophylaxis for cirrhotic inpatients with gastrointestinal bleeding is efficacious in reducing the number of deaths and bacterial infections, are well tolerated, and should be advocated.