Along with the accumulation of evidence to support the use of an oral rehydration solution before surgery, there is a strong tendency for the period of fasting before the induction of general anesthesia to become shorter and shorter. In this study, we compared hunger, thirst, psychology and onset of pneumonia as a sequela in between two groups of surgical patients-one with preoperative rehydration and the other without. The results showed that stress did not build up in the patients given a preoperative oral rehydration solution even after they returned to their rooms and did not have an intravenous drip. No one in either group developed pneumonia after surgery.