Conventional radiographic examinations do not provide unmistakable identification of the so called Stafne's cyst, a little recess on the lingual surface of the mandible. We performed CT scans in four patients and obtained excellent visualization of the bone defect and of the adjacent submandibular gland in all cases, so that it was always possible to diagnose without any doubt the lesion thanks to its definitive real "in vivo" representation.