Background: One of the most frequent side effects is acute and often profound hypotension that increases the risk of perioperative neurological & cardiovascular events especially in elder. The different studies on animal have suggested that serotonin may be an important factor inducing BJR. This is having a significant impact on decreasing the blood volume and helps to change the mechanism that triggering the activation of 5-HT3 receptors that is located in intracardiac vagal nerve endings by serotonin.
 Aim: The aim of the present study is to evaluate the efficacy of intravenous Ondansetron in preventing the incidence of hypotension in non-obstetrical surgical procedures in AGMC & GBP Hospital.
 Methods: Patients of both sexes physical status grade l and ll, age between 20 to 60 years, scheduled for any elective lower abdominal and lower limb surgeries (non-obstetric population) under spinal anaesthesia. The data were collected for both the groups as per the study tools and is depicted in comparative charts. Mean ± SD (Standard Deviation) was calculated for quantitative variables like age, weight, BMI, and MAP.
 Results: The proportion of males/ females in both the groups was almost similar with no statistically significant difference. However a statistically significant difference was marked in the body weight of the two groups. Comparison of the development of nausea after spinal anesthesia between patients in the Ondansetron and Normal Saline groups show that the proportion of patients that developed hypotension was higher in the normal saline group (2.8%) compared to the ondansetron group (0.7%) and the difference between the proportions was not statistically significant.
 Conclusion: The study concluded that ondansetron 4 mg intravenously is an effective prophylactic means of prevention of post spinal anaesthesia induced hypotension within and after 30minutes, maintaining statistically significantly better hemodynamic profiles following spinal anaesthesia and also beneficial to reduce the incidence of postoperative nausea, vomiting and shivering compared to normal saline.
 Keywords: Hypotension, bradycardia, Bezold-Jarisch reflex and Ondansetron