Background and Aims: Inguinal hernia repair is associated with moderate to severe pain that is most extreme in the first 24 hours. The aim of this study was to compare the efficacy of dexamethasone versus magnesium sulphate (MgSO 4 ) with bupivacaine in ultrasound-guided transversus abdominis plane (TAP) block for patients undergoing unilateral inguinal hernioplasty. Methods: Eighty patients were randomly allocated to two groups to receive ultrasound-guided TAP block postoperatively with either 20 ml of 0.25% bupivacaine with 8 mg of dexamethasone (Group BD) or 20 ml of 0.25% bupivacaine with 250 mg of MgSO 4 (Group BM). Patients were assessed for the first 24 hours after surgery for pain at rest and movement using a numerical rating scale (NRS). Two mg/kg of tramadol was administered as rescue analgesia. The time to first demand tramadol, total consumption of tramadol, patient satisfaction score and side effects were evaluated. Results: The time to the first dose of rescue analgesia was significantly longer in BD group (596.13 ± 57.93 min) than in the BM group (422.50 ± 51.95 min). The NRS scores in the BD group were significantly lower compared to the BM group both at rest and on movement. The total requirement of tramadol was significantly less in the BD group (154.55 ± 59.11 mg) compared to the BM group (270.25 ± 105.72 mg). The incidence of side effects was lower and patient satisfaction was higher in BD group compared to BM group. Conclusion: Bupivacaine with dexamethasone in TAP block after unilateral open inguinal hernioplasty provides increased duration of analgesia and decreased requirement for rescue analgesics compared to magnesium sulphate, with lesser side effects and better patient satisfaction.