Context: Persistent vomiting leads to poor patient satisfaction, delayed wound healing, dehydration and electrolyte disturbances. In addition, vomiting or retching can sometimes result in more serious complications like aspiration, wound dehiscence, increased intracranial pressure, oesophageal rupture and pneumothorax. The expanding number of procedures performed as daycare surgeries has led to the increasing use of dexamethasone for PONV. Aims: The present study is to evaluate the optimum dose of dexamethasone for prevention of PONV and to measure the extent of the hyperglycemic side effects post-operatively in non-diabetics. Settings and Design: Prospective randomized controlled comparative study. Methods and Materials: After approval from the Institutional Ethics Committee, study was conducted on 135 patients of the American Society of Anesthesiologists (ASA) Grade I, II and III, aged between 20 to 60 years and included both genders that underwent elective surgeries under general anesthesia. Patients were randomized into 3 Groups to assess the efficacy of different doses of dexamethasone for prevention of PONV. All post-operative cases were followed up at 0, 12 and 24 hours, PONV and blood sugar levels were measured. PONV was being evaluated on a five-point ordinal scale. Statistical analysis used: Percentage analysis was used for categorical variables and the mean and SD was used for continuous variables. ANOVA with Tukey's Post-hoc test was used for the significant difference and for the repeated measures of ANOVA was used with Bonferroni correction to control the Type I error on multiple comparisons. The collected data were analysed with IBM® SPSS statistics software 23.0 Version. Results: Among categorical variables, p values for age (p - 0.611), gender (p - 0.533), ASA status (p - 0.234) with Chi-square testing were not significant. It is interesting to note that only 1 (2.2%) patient had nausea and vomiting in Group C compared to 5 (11.1%) in Group A and 3 (6.7%) in Group B in the immediate post-operative period. Post-operative blood glucose levels varied significantly in different Groups. In Group A blood sugar levels were 106.93 ± 14.426 mg/dl, Group B 117.31 ± 11.791 mg/dl and Group C 129.49 ± 16.170 mg/dl respectively in the immediate post-operative period. Conclusions: The benefits of administering higher doses of IV Dexamethasone should be weighed against the potential side-effects of short-lasting hyperglycemia.