To assess the length and types of root trunk and length of root in a Saudi Population and to correlate the actual measurements with the CBCT measurements. A total of 206 molars were used in this study. CBCT were obtained and subsequently patients were subjected for extraction as the tooth were having poor prognosis. The measurements were carried out on CBCT by using the accompanying software and the actual measurements were carried out with a digital vernier caliper. The mean and SD scores were calculated for actual length of root trunk and length of root and from CBCT method in maxillary and mandibular 1st and 2nd molar in Type of root trunk. Then the actual and CBCT length of root trunk and length of root were compared dependent t test. The statistical signifi cance was set at 5% level of signifi cance (p<0.05). In maxillary arch, the type A root trunk was observed in 55.88% and 39.06%, type B in 44.11% and 59.37% of fi rst and second molars respectively. Type A root trunk was observed in 75.0 % and 55.18%, type B in 25.0% and 44.87% of mandibular fi rst and second molars respectively. The diff erence between the actual length and CBCT length of root trunk was statistically non-signifi cant (p>0.05) and no signifi cant diff erence is observed between actual length of root and length of root measured by CBCT (p>0.05). Knowledge of the types of root trunk type dimension may aid the dental practitioner in diagnosing and planning the treatment of molars with furcation involvement. CBCT may lend comparatively discriminative dimensions of the periodontal defect similar to that of actual measurements.