Purpose: the aim of this study was to define the role of coronoid condylar index (CCI) in diagnosis of elongated coronoid process. Patients and Methods: Eight patients with unilateral coronoid hyperplasia were included in this study, six patients were males and two patients were females, their ages ranged from 19-28years with a mean of 23.5 years. All patients were evaluated both clinically (through detection of range of mouth opening, range of mandibular deviation towards the affected side, presence of palpable crepitation or audible grating in the TMJ and finally vision of movement of the coronoid process in the infratemporal fossa during mouth opening ) and radiographically (from the lateral projection three dimensional computerized tomography of the lower jaw). Results: regarding to the mouth opening, the mean of mouth opening for all patients was 25.3 mm. the mean of deviation of the mandible towards the affected side was 3.5mm. Palpable crepitation and audible grating of the temporomandibular joint had been detected only in three cases. Vision of the coronoid process movement in the infratemporal fossa had been detected only in four cases, particularly during mouth opening. Radiographic evaluation revealed, the mean of the coronoid condylar index (CCI) to all the examined patients was 1.22mm. Conclusion: The CCI is considered as simple and rapid method for determination of any discrepancy in both coronoid and condylar processes of the lower jaw.