The further development of the risk score presented by us in 1976 combined with Peter's score now permits a satisfactory preoperative risk estimation in pediatric surgery for all age groups. The score includes 18 lines for all significant preoperative parameters and the procedure planned. Each parameter is judged by a number of points according to its significance (1-4 points). An increasing number of points indicates an increasing operation risk. The evaluation of 533 cases using this core proved it to be a reliable preoperative risk estimation.