Teeth are vertebrate organs that arise from complex and progressive interactions between an ectoderm, the oral epithelium and an underlying mesenchyme. A significant amount of research has focused on determining the processes that initiate tooth development. It is widely accepted that there is a factor (multiple signaling molecules, including BMPs, FGFs, Shh and Wnt proteins) within the tissues of the first branchial arch that is necessary for the development of teeth. A 9-year-old reported to our department with the chief complaint of pain in the lower right back teeth region. On clinical examination, mandibular molars revealed the presence of an extra cusp on the lingual surface. Occurrence of six cusps in permanent mandibular molar is a rare phenomenon, and number of cases reported is very few.