A prospective study of bacterial and fungal infections after liver transplantation in 284 adults was undertaken. One hundred seventy-five (62%) became infected; bacterial or fungal infections occurred in 159 (56%) and 36 (13%) patients, respectively. Gram-positive cocci, in particular Staphylococcus aureus and Enterococcus faecium, were the commonest bacterial pathogens, and bacteremia and wound infection were the most frequent bacterial infections. Acute rejection and prolonged admission were independent risk factors for bacterial infection; pretransplantation antibacterials had a protective effect. Fungal infection most frequently involved the urinary tract and chest; Candida albicans was the most common pathogen. Four independent variables predicted fungal infection: low pretransplantation hemoglobin, high pretransplantation bilirubin, return to surgery, and prolonged therapy with ciprofloxacin. Patients with acute liver failure were more prone to bacterial, but not fungal, infection. No associations were found between infections and duration of surgery. Bacterial, and to a lesser extent, fungal infections are important complications of liver transplantation. However, liver transplantation surgery per se may not be the major determinant of infection.