Of the many variants in the mandible, the retromolar foramen is the most important. The incidence of retromolar foramen was studied in a collection of 157 south Indian mandibles available at the department of Anatomy, St. John's Medical College, Bangalore. On each side of the mandible, the area behind the last molar tooth was inspected for the presence of retro molar foramen. Wherever present, their distance from the last molar tooth and their size if they were sufficiently large were measured with a sliding caliper to the nearest millimeter. Retromolar foramen were found to be bilateral in 8 mandibles (5.1%) and unilateral 20 [right: 9 (5.7%); left: 11 (7%)] mandibles. The diameter of the foramina was 2 mm on both sides.