Background and Objectives: Microbial invasion to the pulp tissue often leads to pulpal necrosis. This study aimed to assess the size of periapical (PA) lesions of root canals of maxillary anterior teeth irrigated with 0.2% chlorhexidine (CHX) and 5.25% sodium hypochlorite (NaOCl) one year after root canal treatment (RCT) using photostimulable phosphor plate (PSP) digital radiography. Materials and Methods: In this randomized controlled clinical trial, 30 patients with maxillary anterior teeth with PA lesions (1-1.5 mm in size) were selected and randomly assigned to three groups of 10. During RCT, the root canals were irrigated with 0.2% CHX in group 1, 5.25% NaOCl in group 2 and saline in group 3. The teeth underwent PSP digital radiography by the parallel technique at baseline (preoperatively) and at 1 year postoperatively. The small and large diameters of the PA lesions were measured on the radiographs by two radiologists. Statistical comparisons were made using univariate ANOVA and Tukey’s test. Results: The mean reduction in small and large diameters of the PA lesions at 1 year postoperatively was not significantly different between the CHX and NaOCl groups (P>0.05). However, the CHX and NaOCl groups bothshowed significantly smaller PA lesions than the saline group at 1 year (P=0.00). Conclusion: No significant difference was found in the efficacy of irrigation with 0.2% CHX and 5.25% NaOCl for reduction of the size of PA lesions at 1 year, postoperatively. However, both irrigating solutions were significantly superior to saline for this purpose.