Background: Pruritus and nausea vomiting are common side effects of spinal morphine and general anesthesia. Hydroxyzine is one of the antihistamines that are used for treating pruritic and nauseous patients. A randomized prospective double-blind study was undertaken in order to identify the preventive effects of hydroxyzine to prevent pruritus and nausea vomiting in patients who have transabdominal hysterectomy under combined spinal-general anesthesia.Methods: 80 patients scheduled for elective transabdominal hysterectomy under combined spinal-general anesthesia were randomized to receive either hydroxyzine 75 mg and oral midazolam 7.5 mg (atarax or ATR group) or placebo and oral midazolam 7.5 mg (control or C group) as premedication at least half an hour before their operation. Clinical data (vital signs, pruritic score, nauseous score, sedation score, etc) were recorded at pre-operative, intra-operative and 48-hour postoperative periods. All patients had spinal block with 0.5% heavy bupivacaine 2 ml with 0.3 mg preservative free morphine and general anesthesia with thiopenthal sodium 5 mg/kg as induction, intubated with atracurium 0.6 mg/kg and maintenance with nitrous oxide in 50% oxygen and isoflurane. A conventional reversal technique was done in all patients. Intravenous fentanyl was used for pain as needed, oral chropheniramine syrup 2 tsp (4 mg/10 ml) every 4 hours was used for pruritus and intravenous ondanzetron (8 mg) was used for nausea/vomiting in the post-operative period.Results: Pruritus and nausea vomiting were observed blindly 24 and 48 hours post-operation. At 24 hours post-operation, there were 5 patients in the ATR group (12.5%) and 6 patients in the control group (15%) who had mild pruritus. There was no significant difference between the two groups (p = 0.745). At 48 hours post-operation, all patients were free of pruritus. There were 2 patients who had mild nausea (5%) and 2 patients who had moderate nausea (5%) in the control group within 24 hours post-operation. In the ATR group there was no patient who had mild or moderate nausea. There was no significant difference between the two groups (p = 0.152). At 48 hours post-operation, there was 1 patient in each group who had mild nausea (2.5%), which had no significant difference. At 24 and 48 hours post-operation, all patients were free of vomiting.Conclusion: Hydroxyzine cannot prevent pruritus and nausea/vomiting from spinal morphine in patients having transabdominal hysterectomy under combined spinal-general anesthesia.