A psychologic preparation program was developed for use prior to emergency surgery in children. The purpose of this study was to determine whether specific information prior to an emergency operation would reduce anxiety. The effect of the preparation program was evaluated with clinical and laboratory procedures. One group of children who received only general verbal information was compared with another group who received specific information. The subjects were 24 patients and their parents. The children were studied at four different clinical units prior to operation, using the Visual Analogue Scale and pulse rate and blood pressure measurements. Stress hormone levels were measured at three of these clinical units. Visual Analogue Scales were administered to parents three times prior to the child's operation. The results were analyzed for within-group differences from one clinical unit to the next and for between-group differences at the various clinical units. The results indicated less anxiety in the children who received specific information. Catecholamine and β-endorphin measurements were not greatly different between the groups.