Context: Availability of large number of agents which prevent emesis and continued research for newer drugs to treat emesis indicated the magnitude of the problem and lack of satisfactory regimes. Aims: To study the effectiveness of granisetron in reducing the incidence of post operative nausea and vomiting in patients undergoing lower segment cesarean section. Settings and Design: Hospital based cross sectional study was conducted at SVS Hospital and Medical College, Mahabubnagar. Methods and Material: 75 women of ASA gradel and 2 aged between 2035 years weighing between 4565 kg at term posted for elective cesarean section under spinal anesthesia were enrolled for the study. Patients were randomly allotted into three groups of 25 each. Patients belonging to group A received injection Ondansetron 4 mg, group B received injection Granisetron 2 mg and group C received injections normal saline 2 ml IV. Statistical Analysis: Patient data were analyzed by ChiSquare test and p value less than or equal to 0.05 was taken as statistically significant. Results: Incidence of post operative nausea and vomiting (PONV) was more in control group i.e. 44% and it was only 16% in the granisetron group. Among the patients with ondansetron group it was 20%. Granisetron was found to be effective in controlling the vomiting compared to placebo and ondansetron. In group A, 4 patients, in group B, 3 patients and 1 patient in group C had headache. Conclusion: Granisetron 2 mg was slightly more effective than IV Ondansetron 4 mg in preveting PONV following cesarean delivery under spinal anesthesia.