Liver transplantation is complicated by higher rates of bacterial and fungal infection and higher infectious mortality than are other forms of solid organ transplantation. The excess morbidity and mortality are largely confined to the first few months after transplantation and appear to be caused by the technical complexity of the operation and perhaps the residual end organ effects of chronic liver failure. The most common infections seen are bacterial infections in the abdomen and hepatobiliary system, systemic cytomegalovirus infections, bacterial pneumonias, and invasive candidiasis. In addition, systemic viral infections affecting the allograft such as hepatitis B and hepatitis C, adenovirus, and herpes simplex virus have been important clinical problems. The intensity and wide array of infectious problems seen in this population represents a challenge to clinicians to develop strategies for treatment and prophylaxis that will ensure good long-term survival to patients receiving liver transplants.