In the therapy of moderate to severe pain, opioids are generally considered to be an important part of multimodal, perioperative analgesia. There are several potential benefits from using the transdermal route over the oral and parenteral routes for drug delivery. Non-invasive technique, less risk of damage to the gastrointestinal system via the oral route, and the total absence of first-pass metabolism are some of the benefits of this method. It is possible to maintain a steady plasma concentration with a transdermal drug delivery system since it delivers drugs continuously. Analgesics administered in boluses produce toxic and subanalgesic plasma drug concentrations following supra and subtherapeutic dosing. In addition, patients are more likely to comply with their treatment. An abdominal surgery under general anesthesia was performed on 40 patients, who were randomly divided into two groups (n=20). Buprenorphine dose was 10 mcg/h in group A and 25 mcg/h fentanyl in group B. After the procedure, three days were required to observe the pain relief and adverse effects. The demographics and baseline characteristics of the two groups are similar. The visual analogue score in group B was significantly lower on Days 1, 2, and 3 of the study than in group A. The mean level of sedation score was significantly different between groups A and B. In regards to hemodynamic variables (systolic blood pressure, diastolic blood pressure, and heart rate), there were no significant differences between the two groups. 10 out of 20 patients of the population of group A required (18.9%) to take a single dose of rescue analgesic, whereas the population of group B did not require any rescue analgesic (0.00%). (p-value of 0.001) This difference in rescue analgesic requirements is statistically significant. There were adverse effects reported by 20% of fentanyl patients and 18.9% of buprenorphine patients. There was a high incidence of nausea and vomiting associated with the drugs. There were 5.9% and 12% incidences of nausea and vomiting in the fentanyl group and the buprenorphine group, respectively. Fentanyl and buprenorphine transdermal drug delivery system controlled postoperative pain effectively and safely. Compared to buprenorphine, fentanyl is better.