Introduction: The purpose of this study was to find out the prevalence of C-shaped canals configurations in mandibular 2nd molar and to investigate the gender prevalence. Materials and Methods: A sample of 1200 patients’ cone beam computed tomography (CBCT) scans were screened and evaluated by a maxillofacial radiologist assessed the axial, sagittal, and coronal sections. Inclusion criteria applied to 801 patients (452 females and 349 male) aged 14–75 years were included in this study with total of 1567 mandibular 2nd molar was evaluated. Inclusion criteria: Available CBCT images of mandibular posterior teeth with at least one mandibular 2nd molar in the scan, absence of root canal treatment, absence of coronal or post coronal restorations, absence of root resorption or periapical lesions, and high-quality images. Canal configuration was classified by criteria’s which described by Fan et al. (2004): (i) Fused roots, (ii) a longitudinal groove on the buccal or lingual surface of the root, and (iii) at least one cross-section of the canal belongs to the C1, C2, or C3 configuration. Results: Considering 801 patients, 97 (12.1%) patients females 57 (7.1%) and 40 (5%) males had a C-shaped canal with no statistical difference between females and males (P > 0.05). Conclusion: The occurrence of C- shaped canal mandibular 2nd molar is approximately 12.1% and no significant difference was found by gender.