Background: The influence of patient factors such as age, sex, weight, body mass index (BMI) and spatial orientation on operative difficulty of impacted mandibular third molar (M3) surgery is a subject of controversy in the literature. Aim: To assess the risk indicators of operative difficulty of mandibular third molar surgery at our institution. Subjects and Methods: A descriptive crossâsectional study involving patients that presented for wisdom tooth extraction between January 2010 and December 2011. The correlation between patients’ factors such as age, sex, weight, height, BMI, radiographic spatial relationship of the impacted tooth and operation time was determined with Spearman’s rank correlation coefficient. Statistically significant variables were selected for multiple regression analysis to determine which factors contribute most to operative difficulty of M3. P value was set at 0.05. Statistical analysis used SPSS 17.0. Results: Only patients’ age and radiographic spatial relationship showed a statistically significant correlation with operation time (P = 0.038 and 0.008, respectively). Linear regression analysis of patients’ age and angulation of M3 showed that both contribute 44.8% risk of increased operation time (regression coefficient = 0.448), with M3 angulation contributing more significantly to increase in operation time (P = 0.001) than increasing age of the patient (P = 0.005). Conclusions: Findings from this study have shown that increasing age of the patient and the angulation of M3 impaction increases the risk of operative difficulty of the impacted M3 significantly.