Background: Fasting before surgery is still common care in a lot of western hospitals. Overnight fasting can induce postoperative insulin resistance. Insulin resistance has been shown to be related to infectious morbidity. It was shown that postoperative insulin resistance can be attenuated by preoperative intake of a clear carbohydrate-rich beverage. The aim of this study was to investigate whether preoperative intake of carbohydrate-rich beverages could postoperatively influence the immune system. Methods: In this randomized, controlled study, we investigated the effect of surgery on the postoperative immune response in 10 preoperatively fasted patients (control) and 2 groups of 10 patients receiving 2 different carbohydrate-rich beverages preoperatively, by measuring human leukocyte antigen (HLA)-DR expression on monocytes on the day before and on the day after surgery. Furthermore, we studied perioperative fluid homeostasis and preoperative well-being of the patients. Results: HLA-DR expression decreased significantly after surgery in the control group. Patients receiving any of the 2 carbohydrate-rich beverages did not show this postoperative decrease. Fluid homeostasis was not affected in any of the groups, and well-being tended to be better in patients receiving carbohydrate-rich beverages compared with controls. Conclusion: This study suggests that preoperative intake of a carbohydrate-rich beverage can prevent surgery-induced immunodepression and thus might reduce the risk of infectious complications.