Bispectral index parameter is used to guide the titration of general anesthesia. This monitoring improves recovery times and hospital discharges, as well as minimizes adverse events. The objective of this study is the comparison of anesthesia depth monitoring by conventional and bispectral index on nausea and vomiting after urological surgery. 180 participants who were scheduled for abdominal urological surgery were studied. Patients before induction of anesthesia were randomize into two groups with and without bispectral index monitoring. Incidence and severity of nausea and vomiting were recorded every 30 minutes for 2 hours and every 6 hours to 24 hours after surgery. The incidence of postoperative nausea and vomiting in Bispectral index group is 14.4% and 8.9% and in control group 28.9% and 23.3%, respectively. The risk of nausea and vomiting after surgery was reduced by 14.5% and 14.4%, respectively in patients monitored with bispectral index. INTRODUCTION Nausea is the conscious perception of medulla stimulation that is associated with vomiting center and create vomiting response (1). General anesthesia with the use of inhalants can cause nausea and vomiting after surgery (Postoperative nausea and vomiting, PONV). The incidence of PONV is reported about 20-30 percent (2). It seems that multiple-factor can cause PONV and few items such as anesthetic drugs, kind of surgery and personal risk factors is effective on PONV. These factors make into two categories that includes factors out of control by anesthesiologists and factors can control by anesthesiologists. 1. Factors out of control by anesthesiologists: some of these factors are age, gender, past history of PONV and motion sickness, smoking, kind of surgery, operating time and anesthesia time, anxiety of patients and parents. 2. Factors controlled by anesthesiologists: these factors are associated of anesthesia settings, including premedications, kind of anesthesia, anesthesia drugs during surPublished by Australian