To evaluate the potential benefit of varicella vaccine for pediatric liver and kidney transplant patients, we determined the consequences of varicella susceptibility for a cohort of susceptible children (n = 44) who received transplants between July 1986 and June 1990 at the Hospital for Sick Children, Toronto. Costs of these consequences were compared with costs with a hypothetical varicella vaccination program in place. The median follow-up was 11.4 months (range, 2-50 months). Total costs in Canadian dollars to the health service without a program were for varicella-related hospital stay ($135,675) and varicella-zoster immune globulin ($4,322). Costs to parents were for lost time ($13,590) and transport ($414). Assuming a vaccine cost of $30/dose and a 90% vaccine efficacy, a pretransplantation vaccination program would have cost $16,205 and saved $3,132/child ($304 for families and $2,828 for the health service) during the study period. Varicella vaccination prior to solid organ transplantation should reduce morbidity in pediatric recipients and provide considerable savings for families and the health system.