Objective: The aim of this study was to evaluate the effect of maintaining apical patency on periapical healing and postoperative pain levels in teeth with necrotic pulp and apical periodontitis. Method and materials: Fifty mature teeth with periapical lesions were randomly distributed into two treatment groups: patency, and nonpatency (n = 25). Patients were followed up over a 12-month period using clinical and radiographic assessments. The data were statistically analyzed using independent-samples t test and chi-square tests at a 95% confidence level (P = .05). Results: Seventeen teeth in the patency group (85.0%) and 19 teeth in the nonpatency group (86.4%) were classified as being successfully treated (P = .900). Conclusions: Within the limitations of the present study, maintaining apical patency did not affect endodontic treatment outcomes. Keywords: apical periodontitis, mature tooth, necrotic tooth, patency, root canal, success