The perioperative changes in epinephrin-, norepinephrine-, histamin-, C5a- and interleukin-6-levels were studied in 40 patients undergoing cholecystectomy for the diagnosis of acute cholecystitis. All relevant mediator levels could be determined in 38 patients. The outcome was not optimal in 16 of them (42%). In order to evaluate the predictive value of the mediators under investigation for the quality of the patients' outcome, a model based on the Bayes' theorem was developed. Using this model the outcome (optimal vs. not optimal) could be correctly predicted in 30 (79%) of our study patients. This kind of data analysis allows to define states of increased risk for a not optimal recovery based on biochemical parameters.