Introduction. Mandibular prognathism is a facial disharmony characterized by an anterior relationship of the mandible to the upper jaw. Some authors associate the increased volume of the tongue with the development of this anomaly. Currently in the scientific literature it is debated whether the tongue actively shapes the surrounding tissues or adapts to existing conditions. The aim of this study is to evaluate the volume of the tongue at the patients with class III malocclusion compared to class I patients using three-dimensional volumetric analysis based on computed tomography. Material and methods. The three-dimensional calculation of the tongue volume was performed using the technology of virtual surgical planning on 15 subjects with class III compared to class I, based on DICOM data of multidetector computed tomography. Results. As a result of a detailed analysis, the volume of the language was correlated with the values of the angles SNA, SNB as well as the Witts values. Conclusion. In conclusion, we attest to a higher volume of tongue at patients with class III compared to class I