The hormonal responses to surgical stress in adults are well characterized. We hypothesized that children have age-related differences in the "stress responses" to surgery. To test this hypothesis we prospectively studied 98 children (aged 2 to 20 years) undergoing elective surgical procedures under general anesthesia. Preoperative and postoperative (1 hour postoperation) blood samples were obtained and serum prolactin and cortisol concentrations were measured. Patient data were stratified by patient age and length of operation. All patients had significant (P < .05) increases in serum cortisol and prolactin concentrations 1 hour postoperatively as compared with preoperative values. However, there were no significant differences in prolactin and cortisol responses to surgery based on the age, anesthetic technique, or length of operation. Females had higher mean (+/- SD) serum prolactin concentrations (78.41 +/- 62.23 micrograms/L) as compared with males postoperatively (39.8 +/- 21.75 micrograms/L) (P < .05). We conclude the following: (1) children have significant increases in circulating prolactin and cortisol concentrations following surgery and anesthesia, and that those increases are not affected by age, length of surgery, or anesthetic technique; and (2) females have greater prolactin responses to surgery and anesthesia than males.