Background information: Mandibular incisors are associated with high failure rate in endodontic therapy because of presence of two canals. There is no clinical diagnostic method to identify the number of canals in the mandibular incisors. Aim: To assess the correlation between incidence of two canals in mandibular incisors and its bucco-lingual width measured at the cervical third of crown. The secondary aims were to assess the percentage of different levels of canal bifurcation and the discrepancy in radiographic measurement of tooth width. Methodology: 70 extracted human mandibular incisors were included in the study. Using Vernier caliper, the bucco-lingual width at the cervical aspect of each mandibular incisor was measured. RVG image was taken through the mesiodistal plane to assess the number of canals, their level of bifurcation and also the buccolingual width of crown at cervical aspect. Canal configuration was categorised according to Vertucci's classification. Result: From the observations of this study, it is inferred that the incidence of Vertucci's type III canal configuration was 44.28%. Type III canal was found when the bucco-lingual width at the cervical third of crown was greater than 5.68 mm (from ROC curve) with 97% sensitivity and specificity. The bifurcation level of type III canals was 93% at middle – apical third, 3% at coronal, and 3 % at apical third. The spearman's correlation between radiographic measure of buccolingual width and its actual measure was 0.82. Conclusion: Within the limitations of this study, it can be concluded that if the bucco-lingual width at the cervical aspect of a mandibular incisor is greater than 5.68mm, then two canals (type III) can be found in 97% of the mandibular incisors among the South Indian population. The incidence of type III canals was 44.28%; the bifurcation level was mostly at middle third of root.