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Background and Aims Traditionally pain is assessed using self-reported methods such as the Numerical Rating Scale (NRS), which can be affected by communication barriers and individual pain tolerance.The Perfusion index which is one of the common parameters recorded in postanaesthesia care unit (PACU) setup has been evaluated as an objective criterion for postsurgical pain. This prospective, observational study was conducted at a tertiary care cancer institute for evaluating the potential of the perfusion index (PI) as an objective pain assessment tool in oncological surgeries. The aim was to find whether PI could serve as an objective criterion,particularly in the postoperative setting.Methods Total of 120 adult patients, aged 18–80 years, ASA I or II, undergoing elective surface oncosurgery were included. PI and NRS scores were recorded every 30 minutes in the post-anesthesia care unit (PACU). Patients received rescue analgesics when NRS scores exceeded 3. Thereafter changes in PI, heart rate (HR), and non-invasive blood pressure (NIBP) were recorded pre- and post-analgesia.Results From the 120 patients, only 45 (37.5%) required analgesics for moderate pain (NRS > 3),mostly receiving intravenous tramadol. A weak negative correlation (r = -0.200, p = 0.188) was found between changes in PI and NRS. While PI increased slightly after analgesia (median 1.8 to 2.0), which was not statistically significant (p = 0.217). The NRS scores significantly decreased (p < 0.001) from a median value of 4 to 3. Thus, PI and NRS showed weak and inconsistent correlation at various time points.Conclusions The study found correlation between PI and NRS scores as unreliable, suggesting that PI may not be a useful standalone tool for postoperative pain assessment, especially for mild to moderate pain.