We report our experience with 29 symptomatic herpesvirus infections occurring during the course of 87 pediatric transplant procedures performed over the 10-year period, 1973 to 1982. The yearly attack rate ranged from 0.05 to 0.40 case per cumulative patient years at risk. A greater proportion (9 of 14) of children who received more than 10 units of whole blood or packed red blood cells prior to transplantation developed a viral infection compared with those given 10 transfusions or fewer (8 of 25) (P = 0.10). Fever occurred in 22 (76%) children, pulmonary disease in 8 (28%), hepatitis in 11 (35%), leukopenia in 7 (24%), thrombocytopenia in 9 (31%) and central nervous system disease in 3 (10%). Herpesvirus infections were responsible for allograft loss in 7 (24%) patients. However, no differences in the actuarial graft survival curves were noted for transplants performed since 1979 in children with and without viral infection. The etiologic viral agents were cytomegalovirus in 19 (65%) episodes, herpes simplex virus in 8 (28%), Epstein-Barr virus in 2 (7%) and varicella-zoster virus in 2 (7%). Cytomegalovirus-infected patients were younger and more commonly developed primary infection compared with children with herpes simplex virus disease who were more likely to have secondary infection and to manifest a mucocutaneous vesicular rash. We conclude that the etiologic agents and clinical features of herpesvirus infections are similar in pediatric and adult renal allograft recipients. Moreover except for distinctive syndromes such as mucocutaneous vesicular eruption or a central nervous system lymphoma, the various herpes-viruses cause clinically indistinguishable illnesses in pediatric transplant patients with similar end organ involvement and untoward renal consequences.