Objectives Swelling, pain and trismus after the surgical removal of the mandibular third molars are the most common and expected postoperative complications. The aim of this cross-sectional study was to assess the association of those postoperative complications and BMI after surgical removal of the mandibular third molars. Material and methods 84 patients who required the surgical removal of their lower third molar were enrolled in this study and were divided into 4 groups dependent on their BMI. Data were tested by one-way analysis of variance (Welch's ANOVA). The differences were tested by the intragroup using the Games-Howell test. Results The effect of BMI on pain had a statistically significant difference within the first 24 postoperative hours: 4 hours (p=0.014), 6 hours (p=0.034, p=0.049), 12 hours (p= 0.00.P=0.023), and 24 hours (p=0.010). For swelling and trismus in the exception on first postoperative day between underweight and normal weight groups (p=0.026), and underweight and overweight groups (p=0.014) no statistically significant correlation was found Conclusion BMI has an impact on a patient’s early postoperative recovery