Records of 302 root-filled teeth treated by dental undergraduates were reviewed by four lecturers in the Department of Conservative Dentistry, University of Malaya. Preoperative and operative factors were evaluated for their association with postoperative pain experience of patients during the visit immediately after completion of biomechanical preparation. Eighty four percent of patients did not experience any pain after biomechanical preparation whilst the remaining 16 percent only complained of slight or moderate pain. The incidence of pain after biomechanical preparation is not high even when performed by inexperienced undergraduates. Teeth with a pre-existing painful condition had a higher chances of postoperative of pain. The incidence of postoperative pain was halved when teeth were associated with a sinus tract.