Objective: Although many attempts to prevent inadver- tent perioperative hypothermia are known, most surgical patients de- velop inadvertent perioperative hypothermia. Inadvertent perioperative hypothermia can cause serious complications such as surgical site in- fection, morbidity, mortality, increased health care costs, and prolonged hospital stay. The aim of this study is to determine the knowledge and practice of nurses regarding involuntary perioperative hypothermia in the pre- and postoperative period. Material and Methods: The re- search was carried out as a descriptive study with 144 nurses working in the surgical clinics and intensive care units of a tertiary university hospital between 01 September-01 November 2021. The data were col- lected with the “Survey Form”, “Inadvertent Perioperative Hypother- mia Information Form” and “Application Form for Preventing Inadvertent Perioperative Hypothermia Development”. Data were eval- uated using SPSS 25 statistical package program, number, percentage, mean, standard deviation, Kruskal-Wallis Test, Mann-Whitney U Test. Results: The mean age of the nurses was 32±6.91, and the mean inad- vertent perioperative hypothermia knowledge score was 59.09±15.63. It was determined that 79.9% of the nurses did not receive information about inadvertent perioperative hypothermia, 79.9% did not attempt to warm the patients in the preoperative period, and 73.6% of them used blankets to increase the body temperature in patients with postoperative body temperature below 36°C. It was determined that the mean knowl- edge score of the nurses who received information about inadvertent pe- rioperative hypothermia (65.64±13.37) was significantly higher than those who did not (56.12±15.73). Conclusion: It has been determined that the knowledge and practices of the surgical nurses, who are respon- sible for pre- and postoperative patient care, regarding inadvertent peri- operative hypothermia are insufficient. Accordingly, it can be said that nurses should follow the current guidelines for involuntary perioperative hypothermia and that in-service training is needed at regular intervals.