The aim of this study was to investigate the radiopacity of bone graft materials (BGMs) in comparison with bovine mandibular cortical bone and human dentine. Eight samples of each material (8 mm in diameter and 3 mm in thickness) were prepared from Dexabone (R) (DB), Bio - Oss (R) (BO), 4BONE SBS (4B), KASIOS (R) TCP (KA), S. C. PONETI (PO), and Apatite-Wollastonite (AW). The optical densities of each material, along with one tooth section (human canine tooth 1 mm slice), bovine mandibular cortical bone (BC) samples, and an aluminum step wedge, were measured from radiographic images using a transmission densitometer. The data were analyzed by nonparametric one-way ANOVA (Kruskal-Wallis) and Duncan's multiple range tests for post hoc comparison (alpha = 0.05). BC and AW had statistically lower optical density values than BO, 4B and human dentine (p < 0.05). Among BGMs, AW (3.681 +/- 0.409 mm eq Al) had the highest radiopacity values whereas BO (1.925 +/- 0.176 mm eq Al) had the lowest one. The radiopacity values of DB and KA did not reveal a statistically significant difference when compared with other materials (p > 0.05). The radiopacity of all BGMs investigated seemed to be too low to be detected radiographically when placed in the mandibular cortical bone. (C) 2011 European Association for Cranio-Maxillo-Facial Surgery.