OBJECTIVE Selective intestinal decontamination with norfloxacin is useful in the prevention of bacterial infections in cirrhotic patients with gastrointestinal bleeding. However, bleeding cirrhotic patients with ascites, encephalopathy, or shock are at high risk to develop bacterial infections in spite of prophylactic norfloxacin. The aim of this study was to assess whether the addition of intravenous ceftriaxone could improve the efficacy of prophylaxis with norfloxacin in these patients. METHODS Fifty-six cirrhotic patients with gastrointestinal hemorrhage and ascites, encephalopathy, or shock were randomized into two groups: Group 1 (n = 28) received oral norfloxacin 400 mg/12 h for 7 days, and group 2 (n = 28) received norfloxacin plus intravenous ceftriaxone 2 g daily during the first 3 days of admission. RESULTS Ten patients were excluded because of community-acquired infection, surgery, or death within the first 24 h. The incidence of bacterial infections during hospitalization was 18.1% in group 1 and 12.5% in group 2 (p = NS). The incidence of severe infections (spontaneous bacterial peritonitis, bacteremia, or pneumonia) was also similar in both groups: 9% in group 1 versus 8.3% in group 2 (p = NS). There were no statistical differences between the two groups with respect to duration of hospitalization or mortality. The cost of antibiotic therapy (including prophylaxis and treatment of infections) was significantly higher in group 2. CONCLUSIONS These results suggest that the addition of intravenous ceftriaxone during the first 3 days of hospitalization does not improve the cost-efficacy of oral norfloxacin in the prevention of bacterial infections in cirrhotic patients with gastrointestinal bleeding and high risk of infection.