Objectives: Assement of accuracy of maxillary and mandibular linear measurements using different electric potential (KVp) in comparison with real linear measurement .Methods: it was performed on twenty two human dry skulls with mandibles acquired from Anatomy Department, Faculty of Medicine, Cairo University, Qassr El Einy Hospital, 14mm wax used to simulate soft tissue attenuation , The skulls attached to their mandiles were radiographed using Planmeca ProMax 3D Mid CBCT machine (Asentajankatu, Helsinki, Finland) in Oral and Maxillofacial Radiology Department at Faculty of Oral and Dental Medicine, Cairo University All skulls with their mandibles were radiographed using 8 mA, (Ø20cm x 17 cm) field of view (FOV) using stitching and resolution of 400 µm voxel at an exposure time of 27 seconds. For kilovoltage (kVp), each skull was scanned by 3 different settings 90, 80 and 60 kVp. Real measurements were performed using a digital caliper by two experienced radiologists two weeks interval between first and second readings, the results yielded was subjected to Intra- and inter-observer agreement was assessed using Intra-Class Correlation Coefficient (ICC).Bland-Altman plot (differences-vs-means plot) used to show the agreement between two quantitative measurements by studying the mean difference and constructing limits of agreement . Results: there was inter and inter observer reliability ranging from- ICC (0.998 to 0.999) -which was excellent and according to Bland-Altman statistical test there was excellent correlation between measurements at ( 90-80-60 KVp) and real measurements .Conclusion: Maxillary and mandibular linear measurements driven from CBCT images of Planameca Promax 3D Mid® machine using 60, 80, 90 kVp are accurate and reliable for all maxillofacial applications.