This study evaluated the marginal sealing ability of three of the latest generation of dentinal bonding agents following 6 months of storage in a 37 degrees C water bath. Class V preparations were placed at the cementoenamel junction of extracted human molars. Herculite XR was used to restore cavities that had been pretreated with Gluma. Tenure, or XR Bond. The restored teeth were thermally stressed every 30 days during the following 6 months, and then microleakage was assessed by dye penetration. Under the experimental conditions, the microleakage associated with XR Bond and Gluma was not statistically significantly different. XR Bond performed statistically significantly better than Tenure (a = 0.01).