There are quantitative deficiencies in the coagulation system for at least the first 6 mo of life. Clinical experience, however, does not indicate an increased risk of excessive bleeding during surgical procedures. Thrombelastography, a test providing a functional evaluation of coagulation, was used to assess the hemostatic system of pediatric patients under 2 yr of age. Thrombelastographic data were obtained from 237 healthy pediatric patients less than 2 yr of age undergoing elective noncardiac surgery. Five groups were distinguished: under 30 days, 1-3 mo, 3-6 mo, 6-12 mo, and 12-24 mo. Thrombelastography revealed no defects in coagulation when these groups were compared to each other or to adults, indicating a functionally intact hemostatic process even in neonates. Indeed, children less than 12 mo of age were found to initiate and develop clot faster than adults, with the coagulation process slowing to adult rates after 1 yr of age. In addition to defining functional integrity, our data represents a set of pediatric control thrombelastographic values that have not been previously reported and that may become important in understanding coagulation changes that accompany disease states and surgery in pediatric patients.