BACKGROUND: Postoperative shivering is one of the most common adverse effects after general anaesthesia. AIM: This study aimed to evaluate the association between the Bispectral index (BIS) monitoring value and postoperative shivering in patients undergoing orthopaedic surgery. MATERIAL AND METHODS: This cross-sectional study was conducted in Shahid Beheshti Hospital in Sabzevar city, from August 2017 to September 2018. Patients who underwent orthopaedic surgery, using general anaesthesia, were enrolled. Recording of the depth of anaesthesia using BIS monitoring was started exactly 5 minutes after intubating the patient and continued until the discharge from post-anesthesia care unit (PACU). The incidence of postoperative shivering was evaluated using a scale proposed by Crossley and Mahajan. RESULTS: A total number of 80 patients were evaluated. 32.5% of patients experience postoperative shivering grade 2, with mean BIS score 41.85. The univariate and multivariate linear regression analysis indicated a statistically significant relationship between shivering score and patients' heart rate, blood pressure, BIS score, temperature, age, height, gender and blood cell distribution width (RDW) (p < 0.05). CONCLUSION: The results of this study indicate a significant positive association between BIS value and postoperative shivering in patients undergoing orthopaedic surgery, so that, patients with higher BIS score experienced significantly more postoperative shivering. It seems that BIS-guided anaesthesia can reduce the risk and incidence of postoperative shivering in patients undergoing orthopaedic surgery.