Malfunction of the immune system at different levels is typical for patients with liver cirrhosis. Both non-specific as well as antigen-specific functions may be compromised. The best studied and clinically most important problem is the diminished clearance capacity of the reticulo-endothelial system in liver cirrhosis. This transfers into a significantly higher rate of bacterial infections associated with a poorer prognosis in these patients. The clinical relevance of concomitant immune disorders like neutrophil dysfunction is less clear. An impaired activation of natural killer cells (NK) and lymphokine-activated killer cells (LAK) may have a role in the development of hepatocellular carcinoma but additional studies are needed. Clinically important is a moderately reduced efficacy of standard immunization protocols, which can be overcome by an increased dose in most vaccines.