Overreaction of the acute phase response is responsible for the two major complications to surgery, sepsis and thrombosis, but also most likely for the leading sequela to surgery, adhesion formation. The gastrointestinal tract, especially the colon, is a major player in the acute phase response and responsible for important immune functions with important interactions between the commensal flora, mucosal cells and the mucosa/gut associated lymphoid tissues. These responses can effectively be modulated by enteral nutrition, provided it is properly composed and administered. There is increasing evidence that the important clinical effects sometimes observed in enteral nutrition are more related to immunostimulatory effects than to reduction in microbial translocation. It is suggested that in order to be effective enteral nutrition should be instituted if possible before the operation, but always at least immediately after. Furthermore, much supports that the formula given should contain what has been called colonic food, e.g. plant fibres, and have a low content of saturated fat. Use of antibiotics with deleterious effects on the commensal flora should also be limited as much as possible. Lack of compliance with these requests seems to explain the lack of consistency in clinical experience of enteral nutrition, when tried in connection with trauma and clinical surgery.