BACKGROUND:pain, nausea and emesis are common distressing symptoms following general anaesthesia in immediate post operative period. Timing of administration of dexamethasone, ondansetron and their combination for an effective prophylaxis against PONV is an important determinant of their antiemetic efficacy.

Aims: This study aims to compare the efficacy of monotherapy ondansetron I.V, dexamethasone i.v with combination therapy on PONV and to study the incidence & risk factors of PONV.

Settings and Design: This was a randomized, prospective, and comparative study

Materials and Methods: In this study, recruitedpatients were randomly allocated into 4 groups. Groups I, II, III and 4 received IV normal saline, IV Ondansetron 4mg, IV dexamethasone 8mg, IV ondansetron and dexamethasone 8mg, respectively. Incidence, risk factors of PONV and antiemetic properties,complications were assessed and compared among groups.

Statistical analysis: Mean and standard deviation were calculated. Test of analysisbetween groups was done by Chi square, then P value was calculated.

Results: Incidence of PONV was significantly lower in Group 4 (12%) in comparison to Group I (67%)groupII (35%)and Group III (40%).

Conclusion:combinationof IV ondanseton& dexamethasone before GA is safe & more effective than monotherapy. Females, combined H/O motion sickness & previous H/O PONV are considered as reliable predictors of PONV.