Radiopacity is an important property of composite materials for clinical diagnosis. For seven direct composites (Aelite LS Posterior, Aelite All-Purpose Body, Quadrant Universal LC, Clearfil Majesty Posterior, Clearfil Majesty Esthetic, Filtek Ultimate Dentin, IPS Empress Direct Dentin) and six indirect composites (Ceromega, Epricord, Estenia C&B, Tescera, Signum Ceramis, Solidex), disk-shaped specimens (N=260, n=10 per group) were fabricated for two thicknesses at 1 and 2 mm. Average radiographic density of each composite material was calculated. Radiopacity values of specimens were expressed in equivalent thickness of aluminum using the calibration curve. Data were analyzed using one-way and two-way ANOVA, followed by Tukey's HSD test (alpha=0.05). Radiopacity was significantly affected by resin composite type (p<0.05) and thickness (p<0.001). All composites, except Epricord (1.22-1.84), had higher radiopacity values than dentin (1.23-2.24). IPS Empress Direct (5.58-9.38) and Estenia C&B (5.49-9.16) showed significantly higher radiopacity (p<0.05) than the other materials including enamel and dentin.