Objective: Microleakage of tooth-colored restorative systems was tested in preparaiions with and without beveled gingival margins. Method and materials: A resin composite, Z-100, and two componter restoratives, Dyract and Geristor, with their accompanying adhesive systems, were placed in nonretentive cervical cavity preparations (at the cementoenamel junction), with and without a beveled gingival margin (dentin or cementum) and beveled occlusal (enamel) margins in extracted bovine teeth. Microleakage was assessed as the ratio of the extent of meihylene blue dye penetration a! the tooth-restoration interface to the length of the wall. Results; Z-100 restorations, without a gingival bevel, exhibited significantly less microleakage along the gingival wall and less microleakage overall than did ihe other materials. Dyract restorations without a gingival bevel and placed wilhoul a surface conditioner displayed greater microteakage overall than did the other groups. Conclusion: With all materials. Class V restorations with gingival bevels displayed greater microleakage than did nonbeveled margins. (Quintessence Int I998;29:356-36I) Keywords: Class V restoration, gingival margin, mltroleakage, tooth-colored restorative material