The accuracy of two methods of rapidly estimating total body weight in children was assessed. The first method correlated patient length to known total body weight, and the second correlated the weight of both legs weighted together to known total body weight. One hundred children undergoing general anesthesia in the operating rooms of Childrens Hospital of Los Angeles were entered into the study. Each child had a known preoperative body weight. After induction of anesthesia, each child's supine length was measured and hanging (inert) legs were weighted. There was excellent linear correlation between hanging leg weight and total body weight (correlation coefficient [r2], 0.95) for all patients, and good linear correlation between supine length and total body weight, r2, 0.86). Range restriction analysis for both techniques showed poor correlation for total body weights of less than 10 kg and poor correlation for the supine length technique when total body weight was more than 25 kg. The hanging leg weight of an inert child has excellent correlation to total body weight for children weighing more than 10 kg.