Introduction: The World Health Organization sets a standard to maintain patient core temperature greater than 36°C throughout the perioperative period. Normothermia (defined as >36°C) in the Operating Room (OR) is an important factor to preventing complications in patients (MI, infection, coagulopathy). Randomized studies suggests that maintaining at higher temperatures may further reduce complications in surgery (less complications for group at 36.4°C than the control group at 36.0°C) [1,2]. Perioperative normothermia is an important but often unrecognized element during anesthesia. Early recognition of hypothermia would allow for appropriate interventions and prevent complications. Methodology: Manual validation of the diagnostic performance a clinical tool (alert) that would automatically measure changes in core temperature to identify patients who fail to be in range of normothermia during surgery. Results: The clinical tool (alert) was found to be 97 % sensitive.