The incidence of cytomegalovirus infection in Chinese patients was reviewed in a retrospective study of 99 renal transplant recipients. CMV infection occurred in 18 patients (18.2%). In 4 the infection was considered primary and in 14 it was thought to be reactivation. Of the infections 88.9% occurred within the first 6 months after transplantation, 44.4% were asymptomatic, while the rest had protean manifestations with the commonest combinations of fever, hepatic dysfunction and haematological abnormalities. One patient succumbed to the infection. Significant difference was seen in the incidence of CMV infections among patients who had received different antirejection therapy, being the highest (37%) among those who had received either Atgam or OKT3. Among the various secretions, urine gave the best yield of virus cultures.