OBJECTIVE To evaluate the morphology of enamel and dentin margins of Class V restorations filled with different resin composites and glass ionomer cements by SEM examination of replicas. Microleakage was also evaluated between the restorative materials and dentin and enamel at different levels. METHODS Non-retentive Class V cavities were prepared in extracted third molars on buccal and lingual surfaces at the CEJ level. Each material was used according to manufacturer's directions. Immediately after finishing, an impression of each restoration was made using a polyvinylsiloxane material to obtain an epoxy resin replica. Each replica was inspected under SEM to evaluate the morphology of the margin along the cervical-dentin and incisal-enamel junctions. Each tooth was then stored in dye solution (erythrosin B) for 24 hours. First an evaluation was made along the restoration margins to evaluate circumferential leakage. After longitudinal sectioning, leakage was calculated along the cavity wall in dentin and at the enamel interface (longitudinal leakage). RESULTS Enamel margins were characterized (SEM) by prism fractures around restorations along with enamel chips and overhangs. These lesions were observed in about 30% of the samples. Dentin margins showed gaps along the dentin-bonding agents and fractures in the bonding agent/composite interface. Glass ionomers showed similar but fewer lesions both at enamel and dentin interfaces.