Objective: To assess the value of short-term decadron (Dexamethasone) therapy on prevention of post operative nausea and vomiting following caesarean section. Design and method: A randomized control study was done between the 1st of March 2012 and the end of April 2013 at King Hussein Medical Center. During this period a total of 100 full term women scheduled for elective caesarean section under spinal anaesthesia were included in the study. 50 women were given 8 mg decadron injection and another 50 women were considered as control group. The total incidence of nausea and vomiting was calculated. Results: During the study period, 100 women enrolled. There was no significant difference among both groups with respect to age, weight, parity, duration of anaesthesia and surgery. In the decadron group, nausea and vomiting were absent in 62% of patients, while only nausea and vomiting were absent in 22% of patients in the control group. Also 16% had nausea and vomiting in the first post operative period in the decadron group, while 44% had nausea and vomiting in the first post operative period in the control group. Conclusion: Dexamethasone significantly decreased the total incidence of nausea and vomiting in patients who underwent caesarean section under spinal anesthesia compared with the control group. Also dexamethasone injection is simple to administer and provides a safe and very effective antiemetic protection.