Introduction: Opioid is commonly used analgesics for postoperative pain. Various modes of delivering drug are present but transdermal drug delivery system is safe, sustained, non-invasive, better absorption and lack of first-pass metabolism. Bolus dosing results in toxic plasma levels and inadequate duration of analgesia.Methods: It is prospective, randomized, double blind comparative study, conducted after obtaining approval from institutional ethics committee and written informed consent from patients. Patients of age 18-60yrs, undergoing lower limb surgeries under Spinal Anesthesia (SA) with ASA-1 status were included in study. Patients with drug allergy or intolerance to opioids were excluded. Patients’ were randomly assigned into 2groups of 45 each, Group B received Buprenorphine 10mcg/h TDS and group F received 25mcg/h Fentanyl TDS, 6 hours prior to surgery. Patients were followed for three days for postoperative pain relief and adverse effects. Statistics used was Student t-test, Fischer-exact test and Chi-square test.Results: Baseline and demographic variables are comparable in both groups. Mean level of VAS was significantly lower in group Fentanyl as compared to group Buprenorphine. Mean level of sedation score was significantly lower in Group Fentanyl than Group Buprenorphine. Haemodynamic variables in both groups (SBP, DBP and HR) showed no significant difference. 6 out of 45(13.3%) patients in group Buprenorphine required single dose of rescue analgesic while 0 patients in group fentanyl and requirement is statistically significant (pvalue=0.026). 20% patient in Group Fentanyl and 17.8%patients in Group Buprenorphine experienced some adverse effects.Conclusion: Fentanyl and buprenorphine TDS were effective and safe in controlling postoperative pain but Fentanyl is better than buprenorphine in this respect