This study was done on 100 patients in Kasr ElAiny hospital who underwent posterior segment surgery (vitreo-retinal) under general anesthesia. 50 patients received granisetron 1 mg (group G) & 50 received peribulbar block (group P). PONV was assessed during the first 24 hours following tracheal extubation. In this prospective randomized clinical trial, it was found that granisetron 1 mg was more effective in reducing PONV than peribulbar block since nausea occurred in 14% of group G as opposed to 34% in group P. In addition, vomiting occurred in 6% of group G as opposed to 16% of group P. Both therapeutic regimens were safe & well tolerated without any adverse effects or incidence of death. Other factors implied in the results include female gender, age and operation. Female gender was more predominant in PONV. Also PONV incidence declined with increased age. Concerning the type of operation, PONV occurred more frequently in vitrectomies than in retinal surgery.