BACKGROUND The purpose of the present study was to evaluate postoperative pain after root canal treatment at the Department of Conservative Dentistry, Faculty of Dentistry, University of Khartoum, Sudan. METHODS Two hundred thirty-four patients were included in this study; age range was 18-62 years. Conventional endodontic treatment was carried out in the included teeth by the undergraduate dental students in a single visit or multiple visits. The chemomechanical preparation of root canals was done by a modified double-flared technique with combination of hand instruments. Postoperative pain was recorded by each patient by using visual analogue scale in well-defined categories at 2 time intervals, 12 hours and 24 hours. RESULTS Data were analyzed with the chi(2) test. The overall incidence of postoperative pain was 9.0% after 12 hours and 24 hours. Postoperative pain developed in 15.9% of the patients with history of preoperative pain, whereas 7.1% had postoperative pain among those without history of preoperative pain. There was no significant difference in postoperative pain between single-visit and multiple-visit root canal treatment (RCT). CONCLUSIONS Within the limitations of the present study there was a low incidence of postoperative pain after conventional RCT. No significant difference exists in postoperative pain after single-visit or multiple-visit RCT.