Purpose : The purpose of this study was to find effects of early oral water intake on thirsty feeling, nausea, and vomiting after ambulatory surgery. Method : Sixty patients who received PET(Pressure Equalizing Tube) insertion surgery under general anesthesia were conveniently sampled and divided into two groups. Experimental group was instructed to drink water after two hours and control group was directed to intake water after three hours postoperatively. Data were collected from May 1, 2002 to August 31, 2002 at ambulatory surgery center of Asan Medical Center. The thirsty feeling, nausea and vomiting score between experimental and control group were compared at the time of recovery, recovering consciousness, 2hr, 3hr, right before discharge and/or 24hr(telephone interview) postoperatively. The collected data were analyzed by SPSS 8.0 statistic program. Result: Result of this study are as follows. 1) There was a statistically significant difference(t=-10.31, p=0.00) in the occurrence of thirsty feeling at the 3hr postoperatively between experimental and control groups. 2) There was a statistically significant difference(x²=6.66, p=0.02) in the incidence of nausea during the 2hr postoperatively between experimental and control groups. 3) There was no difference(x²=0.35, p=0.55) between groups in vomiting scores. Conclusion : It was generally known that the delay of oral water intake decreases post operative complications. But, this study shows that early oral water intake decreases discomfort of thirsty and there was no adverse effects on the occurence of postopeative nausea and vomiting.