Infection is the main cause of death following renal transplantation. In the literature 7 fatal cases of toxoplasmosis following renal transplantation have been described. In the present papers a case of reactivated toxoplasmosis is presented where the patient survived. Fortuitous withdrawal of therapy and transplant nephrectomy may have been responsible for the patient's survival. The problems of diagnosis of toxoplasmosis following renal transplantation are discussed. Early diagnosis is vitally important as successful treatment of toxoplasmosis with pyrimethamine and sulfonamides in patients receiving immunosuppressive therapy has been reported. It is emphasised that reaction of toxoplasmosis should always be considered in patients with fever of unknown origin and cerebral symptoms.