AIM: To assess the interrelation of tongue posture with the dentoalveolar maxillary and mandibular morphology in a group of class III and class II subjects in comparison to a group of class I subjects. MATERIALS AND METHODS: 30 pre–treatment lateral cephalograms and dental caste was evaluated. 30 subjects were divided into three groups according to the sagittal jaw relations. Tongue posture was determined in six different points in terms of tongue–to–palate distance. The arch widths were evaluated on the dental casts. RESULT: In Class II subject, Mean value of arch width in maxilla were narrow and tongue posture is high compare to Class III and class I subjects. Tongue posture had a weak correlation with dental arch width in all subject groups. CONCLUSION: Significant difference in term of tongue– to – palate distance was found at middle portion of tongue in different skeletal sagittal pattern. No significant different was found in dentoalveloar arch form.