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The aim of this study was to evaluate the wear properties of opposed dental ceramic restorative CAD/CAM materials and several posterior direct restorative composite resins. Three kinds of dental ceramics CAD/CAM materials (monolithic zirconia, lithium disilicate, leucite) and four dental composite resins&#8212;that is, MI Gracefil, Gradia Direct P, Estelite &#931; Quick, and Filtek Supreme Ultra&#8212;were used in this study. For each of the 12 groups (three ceramics &#215; four composite resins), five each of a canine-shaped ceramic specimen and a cuboidal shape opposing composite resin were prepared. All of the specimens were tested in a thermomechanical loading machine (50 N, 100,000 cycles, 5/55 &#176;C). Wear losses of ceramic specimens and composite resin specimens were evaluated using a three-dimensional profiling system and an electronic scale, respectively. Statistical analyses were performed using the Kruskal&#8722;Wallis test and Mann&#8722;Whitney U test with Bonferroni&#8217;s correction. Zirconia showed significantly less volumetric loss than lithium disilicate or leucite regardless of composite resin type (<i>p</i> &gt; 0.05/3 = 0.017), and that Estelite &#931; Quick showed significantly more weight loss than Filtek Supreme Ultra, MI Gracefil, or Gradia Direct P regardless of ceramic type (<i>p</i> &gt; 0.05/6 = 0.083). Zirconia showed less volumetric loss than lithium disilicate or leucite. Some composite resins opposing ceramics showed considerable weight loss.