Background and objective: Diagnosis of Horizontal Root Fractures (HRF) is based on clinical and radiographic documents. The aim of this study was to compare the diagnostic accuracy of digital Periapical Radiographs (PSP) with different angulations in different locations and Cone Beam Computed Tomography (CBCT) in the detection of HRF in central and lateral maxillary incisors. Materials and Methods: For this experimental study, 60 human central and lateral maxillary incisors were selected and were divided into 4 groups and were numbered. Root fractures were created by using mechanical force in the apical third, middle and cervical part of roots in the groups 1 to 3. The last group was considered as a control group without any fractures. The two fragments from each tooth were relocated with super glue. Then, the radiographic images of all the teeth were taken using digital PSP and CBCT methods. Afterward, two oral and maxillofacial radiologists assessed the images separately. The data were subjected to specificity and sensitivity for each radiographic technique. The kappa statistics were used for assessing the agreement between observers. The Significance level was considered as P<0/05. Results: CBCT method had higher specificity and sensitivity in the detection of HRF compared to PSP. Kappa value for inter-observer agreement in HRF was 0/89 for CBCT and 0/725 for PSP. Conclusion: CBCT outperformed the PSP method in detecting simulated HRF. CBCT should be used as the reliable imaging method for the diagnosis of HRF.