Recognizing the problems of thromboembolism and anticoagulation in children and the high incidence of calcification in porcine valves in children, we hoped that the Ionescu-Shiley valve might be a good choice in the younger age group. We implanted 2,372 Ionescu-Shiley valves in 2,167 patients between 1978 and 1982, of which 30 were in children 16 years of age and younger. Although there have been no known instances of thromboembolism, valve infection, or valve disruption in this group of children, seven (23%) have already required reoperation for calcific stenosis. Although calcification appears maximal in postpubertal children less than 17 years of age, we consider it unwise currently to place these valves in any child and have returned to mechanical valves for this purpose.