BACKGROUND: The role of propofol on the inflammatory cytokine response during surgery has been contradictory. This study was conducted to evaluate the effect of propofol compared to that of enflurane on cytokine responses. Pro- and anti-inflammatory cytokines, interleukin (IL)-10 and IL-12, were measured. METHODS: Thirty patients, who underwent colo-rectal cancer surgery, were randomly assigned into two groups in double-blind fashion. One group (n = 15) was anesthetized with enflurane vapor anesthetic, whereas the other group (n = 15) was anesthetized with a propofol intravenous infusion. At predetermined time intervals, the changes of IL-10 and IL-12 were measured. In addition, vital signs, amount of fluid infused during the operation, estimated blood loss and total amount of pethidine given within 24 hours after the operation were also measured. RESULTS: There were no statistically significant differences in the changes of IL-10 and IL-12 concentrations at all intervals when compared between the two groups, although the IL-10 was significantly increased at 1 hour after incision within each group. No other measured variables showed any meaningful differences. CONCLUSION: This study has demonstrated that propofol anesthesia did not prevent the surgical stress provoked cytokine responses.