Recently several new bonding agents that show promising in vitro performance have been marketed. Frequently there is inconsistency between in vitro test results and in vivo performance of new adhesive materials. This investigation was designed to evaluate the micromorphologic relationship between in vivo and in vitro dentin after application of two new dentinal bonding systems. V-shaped cavities were restored in vitro and in vivo with Gluma 2000 bonding system a nd Pekafill composite resin and Scotchbond Multi-Purpose bonding system and Z100 composite resin. After dissolution of dental structures, the restorations were observed with scanning electron microscope. No morphologic differences were found between in vivo and in vitro specimens of eithe rdentinal adhesive system. Intertubular and peritubular dentin was reproduced accurately in every specimen.