Aim of the Study: The aim of this study was to evaluate theeffects of systemic intramuscular route versus local endoalveolaradministration of Dexamethasone on the postoperative pain, swellingand trismus following impacted lower third molar surgery.Patients and Methods: Thirty patients underwent surgicalextraction of lower third molars and were randomly assigned to receiveeither 8 mg Dexamethasone by intramuscular injection (group A) or 10mg Dexamethasone as endo-alveolar powder (group B). Facial edema,trismus and pain perception were evaluated at the 2nd, 5th and 7thpostoperative days.Results: There was no statistically significant differencebetween the two groups concerning pain, edema and trismus followinglower third molar surgery throughout all periods of follow up, althoughdirect endoalveolar application of Dexamethasone powder resulted inearlier resolution of facial edema & less pain at the secondpostoperative day postoperatively compared to the parentalintramuscular injection.Conclusion: Endoalveolar application of 10 mg ofDexamethasone was more effective than intramuscular administrationof 8 mg in reducing postoperative swelling and pain.