INTRODUCTION: Graft rejection and infection remain major morbidities following orthotopic liver transplantation (OLT). Rejection treatment may be associated with an increased rate of infectious complications. The aim of this study was to determine the relationship between rejection, rejection therapy and the risk of associated infections. MATERIALS AND METHODS: A retrospective study of all adult patients undergoing OLT between July 1987 and July 1997 at a single university medical centre was carried out. Data for all transplant recipients were collected using predetermined definitions for infectious complications. RESULTS: One hundred OLTs were performed on 98 patients (two patients received a second transplant). The cohort consisted of 33 women and 65 men with a mean age of 47 years. Seventy-eight patients developed a total of 228 infectious episodes: 107 bacterial, 101 viral, 17 fungal and 3 protozoan. The majority of infections occurred within the first month of OLT. Thirty patients without rejection developed 42 infectious episodes, whereas 70 patients with at least one treated rejection episode developed 186 infectious episodes. The overall rate of infection was 44.4 episodes per 1000 patient-days in the 30 days before rejection, and 94.4 episodes per 1000 patient-days in the 30 days following rejection treatment. CONCLUSIONS: Infections occurred more frequently during the first month post-transplantation. Following OLT, rejection is associated with a higher incidence of infection, mainly of viral origin, concurrent with increased immunosuppressive therapy.