Infection has been the major cause of death and morbidity in patients undergoing cardiac transplantation at Groote Schuur Hospital. Twenty-two (55%) patients suffered at least one major episode of infection, which accounted for 10 (59%) of the deaths in the first year. The major site of origin of infection was the lung, though dissemination was not infrequent. Bacteria accounted for 22 (59%) infections; but viral, fungal and protozoal infections were not uncommon and in fact accounted for seven (64%) of the fatal infections. Several unusual causative microorganisms have been isolated in this group of immunocompromised subjects. There is a higher incidence of infection in patients over the age of 35 years and in patients who did not comply with instructions and advice.