Epidermoid cysts, true dermoid cysts and teratoid cysts compose the spectrum of cystic teratomas, which are defined as neoplasms whose tissue are derivatives of more than one germ layer, foreign to that part of the body from which the tumor arises. Epidermoid cysts of the floor of the mouth are rare lesions and are much less common than dermoid cysts in the head and neck. This case reports a 43-year-old male patient who presented with a longstanding midline swelling in the submental region. Initial imaging was done using ultrasound followed by computed tomography (CT) scan. Biopsy was taken and revealed a cyst wall lined with epidermal squamous epithelium along with areas of focal ulceration suggesting chronic inflammatory changes of the wall of the epidermoid cyst. There are characteristic and even pathognomonic imaging features of epidermoid cysts at the floor of the mouth in ultrasound and CT scan. Imaging has an important role in the surgical management plan according to the size and location of the cyst in relation to geniohyoid and mylohyoid muscles.