A thorough knowledge of dental anatomy of both the permanent and primary dentition is essential for all treatment aspects of these teeth. All too often, the study of the anatomy of primary teeth is given secondary importance due to the fact that these teeth will exfoliate eventually. Rather than premature extraction, the retention of primary teeth through restorative or endodontic means is evolving amongst dental practitioners and endodontic and pediatric dental specialists. Thus, knowledge of the normal and abnormal anatomy of primary teeth is required in making diagnosis and treatment decisions in young patients. In rare incidences, as in cases of absent permanent premolars, primary teeth may be retained in the permanent arch and if the pulp becomes diseased, endodontic treatment may be among the treatment options. This article provides a comprehensive review of normal and abnormal morphology of the primary teeth with an emphasis on the roots and root canal systems of each of the teeth in the primary dentition.