To investigate the root and canal morphology of mandibular permanent teeth collected from an indigenous Turkish population. A total of 1400 extracted mandibular permanent teeth were evaluated. The teeth were divided into seven groups as central incisors, lateral incisors, canines, first premolars, second premolars, first molars and second molars in order to evaluate their root canal configurations. Access cavities were prepared and pulp tissue removed using 5.25% sodium hypochlorite solution. The teeth were stored in 5% nitric acid solution for 5 days, then rinsed under running water for 4 h and placed in increasing concentrations of ethyl alcohol. The teeth were rendered transparent by immersion in xylene solution for 3 days until complete transparency was achieved. Following this procedure, India ink was injected in the root canal systems and their configurations were examined and compared with the classification of Vertucci. The following observations were made: (i) root canal classification of mandibular teeth; (ii) morphology of the mandibular permanent teeth. The classification of Vertucci was taken as a reference during the evaluation; however additional canal morphological types were evaluated as separate groups. The presence of a second canal was detected in 68% of mandibular central incisors and 63% of lateral incisors. Lateral canals were found in 6.5% of mandibular central incisors and in 13% of lateral incisors. Overall, 62% of mandibular first premolar teeth had a single canal whereas 71% of second premolars had a single canal. The mandibular first and second molar teeth exhibited similar root canal configurations except for a group of second molar teeth that had a single root and canal. The morphological characteristics of teeth in this Turkish population were consistent with those of other studies performed on different populations using similar methodology.