The aim of this study was to identify the position of impacted mandibular third molars based on the classifications of Pell & Gregory and Winter, the indications for extraction, and the relation of post-operative complications and position. Records of patients who attended Hospital Universiti Sains Malaysia between January and December 2007 for surgical removal of mandibular third molars were reviewed. The angulation type, width and depth of impaction were determined by reviewing the orthopantomograms. The indications of extraction and occurrence of any post- operative complications were recorded. A total of 238 impacted teeth were surgically extracted from 194 patients (97 males, 97 females). The reasons for extraction include recurrent pericoronitis (43.1%) followed by prophylactic purposes (33.5%). Mesioangular impactions accounted for 52.3% and Class IIA position of impaction accounted for 45.7% of extractions. The most common post-operative complication was persistent pain and swelling (14.7%) followed by trismus (4.1%) and dry socket (3.0%). There was no significant relationship between the angulation, width and depth of impaction and the occurrence of complication. Mesioangular type and Class IIA position of impaction were the most common impaction. Although the association was not significant, high frequency of post-operative complications was observed in mesioangular, horizontal, IIA and IIC positions.