Purpose: To compare through digital radiographic analysis the radiodensity levels of seven prefabricated post systems inserted in root canals of bovine extracted incisors. Methods: 21 bovine teeth were cut 15 mm from the apical limit. The canals were prepared according to the manufacturer's instructions using specific bur of each post system analyzed: three metallic posts: Flexi-Flange, Radix-Anker, and FKG post; one zirconium ceramic post: Cosmopost; one carbon fiber post: C-Post; one carbon fiber post system covered with quartz fiber: AEsthetic Post; and one glass fiber reinforced post: FibreKor Post. Root tooth digital analyses were made with Digora system with and without the insertion of post. Their variations were obtained subtracting radiodensity of the post from radiodensity of the root canal, in cervical, medium, and apical thirds of the root canal. Two-way ANOVA and Tukey test (P< 0.05) were used to analyze the data. Results: This study showed that the radiopacity of post systems is dependent on their composition. Statistical differences were found among radiodensity levels in apical third, medium and cervical thirds for all post systems inside the root canals. Statistical differences were also found among the post systems: ceramic posts showed the highest radiodensity level, followed by metallic posts, carbon fiber posts, glass fiber posts, and the carbon fiber post covered with quartz fiber. These results indicate that biomechanical post systems have low radiodensity levels.1815760