To compare the marginal leakage of CAD/CAM-fabricated ceramic inlay, gold inlay and amalgam, forty extracted caries-free premolars were prepared with Class II MO cavity design. The teeth were divided into four groups of ten samples each. Group 1 was restored with CAD/CAM-fabricated ceramic inlays cemented with Scotchbond Resin Cement / Scotchbond Multi-purpose plus. Group 2 was restored with gold inlays cemented with Scotchbond Resin Cement / Scotchbond Multi-purpose plus. Group 3 was restored with gold inlays cemented with zinc phosphate cement. And, Group 4 was restored with amalgam. All samples were thermocycled, and stored in 1 % methylene blue. Marginal leakage was examined at four margins, that is, occlusal distal, priximal gingival, occlusal facial and occlusal lingual margins from sectioned samples under stereomicroscope(x15). The results were as follows : 1. Group 1 and 2 showed no statistically significant difference among marginal leakage at all four examined margins(p>0.05). 2. Group 3 and 4 showed significant marginal leakage at proximal gingival margin compared with other margins(p<0.05). 3. Significantly increased marginal leakage at priximal gingival, occlusal facial and occlusal lingual margins in group 3 were observed compared with other groups (p<0.05).