The aim of this study was to evaluate the radiopacity of the core and veneer ceramics in four zirconia-based crown systems: In-Ceram Zirconia, In-Ceram YZ, Procera Zirconia, and Cercon. Two-millimeter-thick restoration slices were prepared and digitally radiographed alongside an aluminum stepwedge. The grayscale data were converted into millimeters of aluminum by an image analysis program. The two-way analysis of variance test detected significant differences with respect to all-ceramic system, layer ceramic, and the interaction of the two factors (P = .0001). All materials presented radiopacity values above the minimum recommended by the International Organization for Standardization. Int J Prosthodont 2011;24:144–146.