his study evaluated the marginal sealing ability of three of the new generation of dentinal bonding agents. Class V preparations were placed at the cementoenamel junction of extracted human molars. The restored teeth were thermally stressed for 100 temperature cycles and placed in a dye solution for 24 hours. Microleakage was measured under a microscope at × 50 magnification. Under the experimental conditions, there was its significant difference in the performance of the bonding systems.