Bacterial infections are well described complications of cirrhosis that greatly increase mortality rates. Two factors play important roles in the development of bacterial infections in these patients: the severity of liver disease and gastrointestinal haemorrhage. The most common infections are spontaneous bacterial peritonitis, urinary tract infections, pneumonia and sepsis. Gram-negative and gram-positive bacteria are equal causative organisms. For primary prophylaxis, short-term antibiotic treatment (oral norfloxacin or ciprofloxacin) is indicated in cirrhotic patients (with or without ascites) admitted with gastrointestinal haemorrhage (variceal or non-variceal). Administration of norfloxacin is advisable for hospitalized patients with low ascitic protein even without gastrointestinal haemorrhage. The first choice in empirical treatment of spontaneous bacterial peritonitis is the iv. III. generation cephalosporin; which can be switched for a targeted antibiotic regime based on the result of the culture. The duration of therapy is 5-8 days. Amoxicillin/clavulanic acid and fluoroquinolones--patients not on prior quinolone prophylaxis--were shown to be as effective and safe as cefotaxime. In patients with evidence of improvement, iv. antibiotics can be switched safely to oral antibiotics after 2 days. In case of renal dysfunction, iv albumin should also be administered. Long-term antibiotic prophylaxis is recommended in patients who have recovered from an episode of spontaneous bacterial peritonitis (secondary prevention). For "selective intestinal decontamination", poorly absorbed oral norfloxacin is the preferred schedule. Oral ciprofloxacin or levofloxacin (added gram positive spectrum) all the more are reasonable alternatives. Trimethoprim/sulfamethoxazole is only for patients who are intolerant to quinolones. Prophylaxis is indefinite until disappearance of ascites, transplant or death. Long-term prophylaxis is currently not recommended for patients without previous spontaneous bacterial peritonitis episode, not even when refractory ascites or low ascites protein content is present.