Six patients with toxoplasmosis complicating renal transplantation are described, and 25 other reported cases are reviewed. The mean age of the 31 patients was 35.16 years. Most of the recipients (25 of 29) showed signs of toxoplasmosis within 3 months post-transplantation, with fever, neurological disturbances, and pneumonia as the main clinical features. Diagnosis was established at autopsy in 15 cases, by serology in 13 cases, and by direct examination, culture, or polymerase chain reaction of biological samples in 5 cases. Seventeen patients also had concomitant infections. The donor was the likely source of transmission to 10 recipients; reactivation was suspected in two cases. The source of transmission could not be determined for the remaining 19 patients. The mortality rate was 64.5%. Ten of the 11 patients given specific treatment survived, indicating that early diagnosis and therapy are essential.