The present study examines the incidence, risk factors, bacteriology, and mortality of infectious episodes and the role of antimicrobial prophylactic regimens after OKT3 induction in liver transplantation. Infections occurring in the first 6 months were evaluated according to the Centers for Disease Control criteria in 102 transplant recipients. Patients were administered OKT3 for 5 to 10 days, beginning intraoperatively, azathioprine, low-dose prednisone, and delayed introduction of cyclosporine. There were 140 major and 30 minor infections for an incidence of 1.7 infections per patient. Twenty-seven patients (26%) had no infectious episodes during the 6 months of followup. Bacterial and fungal infections peaked during the first month posttransplantation, whereas viral infections peaked during the second month. Infection-related mortality was 10%. One-year survival rate of patients who suffered a major infection was less than those who were infection free, but the difference was not statistically significant (79% vs. 89%; P β«Ψβ¬ .61). There was a significantly higher incidence of enterococcal infections under cefotetan prophylaxis than under ampicillinsulbactam (.375 vs. 11 infections per patient; P β«Ψβ¬ .0017). There were 14 episodes of cytomegalovirus disease (14%) but no cytomegalovirusrelated mortality or graft loss, and all cases responded to ganciclovir treatment. Bivariate and multivariate analyses identified only retransplantation as a risk factor for infection. In conclusion, OKT3 induction after liver transplantation is associated with a manageable incidence of bacterial, viral, or fungal infections. This is caused by, at least in part, improved anti-infective prophylaxis.