Aim: To investigate the root canal morphology of mandibular incisors in a northeast Indian population, using a root canal staining and tooth-clearing technique. Methodology: A total of 480 extracted mandibular incisors, collected from dental clinics within northeast India, were selected for the present study. Following pulp tissue removal, the teeth were decalcified with 5% nitric acid, dehydrated with increasing concentrations of alcohol and rendered clear by immersion in methyl salicylate. After staining the root canal systems with Indian ink, the cleared teeth were examined under 5× magnification, and the following features were evaluated: (i) number and type of root canals; (ii) location of apical foramina; (iii) presence and location of lateral canals, anastomoses and ramifications; and (iv) bifurcation of root canals. Results: The majority of mandibular incisors had a single root canal (63.75% of teeth possessed a Type I canal system). Although 36.25% of the roots possessed two canals, only 6.25% had two separate apical foramina. Conclusions: The prevalence of two root canals in this group of mandibular incisors was 36.25%, within the range of results from previous studies performed on populations of different racial origins. Schlagwörter: anastomoses, lateral canals, mandibular incisors, morphology, root canal types