From November 1985 to August 1987, 22 children underwent orthotopic liver transplantation (OLT). Primary cytomegalovirus (CMV) infection was observed in 3 of 10 seronegative recipients (30%). It was severe in 2 cases, which were treated successfully by a combination of DHPG and CMV hyperimmune globulin. From September 1987 to August 1988, a virologic survey was undertaken. It enabled us to take prophylactic measures and to make an early diagnosis of CMV infection, permitting early antiviral treatment. During this period, 26 children received liver grafts. Nine of 13 seronegative recipients (69, 2%) developed primary CMV infection. Seven had received immunoprophylaxis and 8 were treated by DHPG. None had severe disease and all improved rapidly.