© 2020, Japanese Association of Anatomists.It is aimed to better recognize the mandibular variations by understanding the diversity and positions of accessory foramina better. Accessory formations on a full-term fetal mandible dissected for a mandibular study were examined under a microscope. To observe these formations more clearly, they were photographed with the help of a camera and microscope. In one of the mandibles dissected for a fetal mandibular study, a lateral accessory foramen (LAF1) was detected in the right half just near the mental foramen, and also a medial accessory foramen (MAF1) was detected over the mandibular foramen. In the left half, on the lateral surface relative to the mental foramen, one in the medial (LAF3) and one just above it (LAF2), and last one is near to the ramus of mandible (LAF4), three lateral accessory foramina, were detected. Again, a medial accessory foramen just above the left mandibular foramen (MAF3), and another foramen is near to mandibular symphysis (MAF2), also two medial accessory foramina on the lateral surface were detected. Detection and recognition of such variations are quite important for clinicians in the diagnostic methods and prevention of possible surgical complications.