Aim of the study: The aim of the present paper is to determine the diagnostic features of the rare presentation of osteochondroma in the mandible. The unusual aspect in this case is that the diagnosis was not established with cone beam computer tomography, which is a commonly used radiographic technique in dentistry, but with the use of ultrasonography. Case description: Ultrasonography is very useful for initial examinations, avoiding patient exposure to additional radiation and setting the diagnosis in debatable soft tissue involvement of various lesions. In the presented case, even though the clinical presentation was indicative, the cone beam computer tomography evaluation could not confirm the diagnosis, so the final diagnosis was made by ultrasonography. Conclusions: With the latest advances in the applications of ultrasonography in the maxillofacial region, an examination of lesions on the floor of the mouth or in the neck area may set the diagnosis in cases where hard tissue imaging does not provide enough information.