This study determined the radiopacity of 21 commercially available direct esthetic restorative materials with reference to an aluminum step wedge and an equivalent thickness of enamel and dentin. A total of 168 samples measuring 6 mm in diameter and 1 mm in thickness, with eight samples of each material, were prepared from restorative materials. Enamel and dentin samples 1-mm thick were also prepared by longitudinally sectioning eight extracted human permanent molars using a microslicing machine. The optical densities of each restorative material, along with one tooth section and an aluminum step wedge were measured from radiographic images using a transmission photodensitometer. The optical density values of the specimens were used to determine the aluminum thickness equivalent values. The data were analyzed with one-way analysis of variance (ANOVA) and Duncan's multiple range tests. The results showed statistically significant differences among materials. Tetric Ceram had the greatest radiopacity value and was higher than enamel. All materials except for the microfilled resin composite Filtek A 110 had radiopacity values greater than dentin and possessed sufficient radiopacity to meet ISO 4049 standard. Significant differences were found among materials of the same composition when compared to enamel.