Introduction: Cone beam computed tomography (CBCT) can provide dentists with high-quality 3-dimensional images of dental structures because of its high spatial resolution. The reconstructions of root canal systems given by the Kodak 9000 3D were compared with histologic sections to evaluate the reliability of the reconstructions. Methods: Nine intact freshly extracted teeth with closed apexes were scanned by using the Kodak 9000 3D (spatial resolution 76 mm and 14 bits contrast resolution). After reconstruction of the volumes, the outline of the root canals was defined by segmentation. Histologic sections were then made of each specimen at predetermined levels. After digitiza-tion (resolution, 0.5–1 mm), 2-dimensional cone beam reconstructions were compared with the outline of the canals obtained by histologic sections by using areas and Feret's diameters. The statistical analysis was performed by using the Pearson correlation coefficient. Results: Strong to very strong correlation was found between the data acquired by using CBCT and histology: r (area) = 0.928; r (diameter) = 0.890. Conclusions: The Kodak 9000 3D appears to be a very interesting, reliable, noninvasive measuring tool that can be used in all spatial planes. (