To evaluate the effects of 1) wall grinding status, 2) thermal stress, and 3) time of polishing on sealing performance of two one-step bonding systems in cervical cavities. Semicircular cavities with dimensions of 3 x 3 x 1.5 mm were prepared along the CEJ of extracted human premolars. In experiment 1, the cavity walls were additionally ground with round steel diamond burs (regularly ground) or finished with superfine diamond burs. The cavities were treated with AQ Bond (AQ) or One-up Bond F (OB) and filled with a resin composite. Then thermocycling (5°C to 55°C, 1000 x) was performed. In experiment 2, the regularly ground cavities were used. After restoration, the teeth were subjected to thermocycling (1,000 to 5,000 x). In experiment 3, the restorations in the regularly ground cavities were polished immediately or 24 h after filling. No thermocycling was carried out in this group. All specimens were immersed in a dye solution for 2 h. Microleakage at coronal and apical walls was evaluated on the longitudinal sections of the restorations. For OB, the cavities finished with superfine burs exhibited more microleakage at the coronal wall than the regularly ground cavity (p 0.05). The leakage at the coronal walls increased with the number of thermal cycles for both systems (p 0.05). The delayed polishing generated better adaptation at the apical wall of AQ and at the coronal wall of OB (p 0.05). Grinding status, thermocycling, and time of polishing had influences on the sealing performance of the two one-step adhesive systems. Keywords: microleakage, one-step adhesives, cavity adaptation