The purpose of this study is to evaluate microtensile bond strength (mu TBS) of an etch-and-rinse adhesive to enamel and dentin after treatment with Er:YAG laser using different pulse durations. Extracted human molars were flattened to obtain enamel or dentin surfaces. The enamel specimens (E) were divided into nine groups and the dentin (D) specimens were divided into seven groups according to the surface treatments (n = 6). E-C: acid was applied according to the manufacturer's instructions and used as control, E-SSP: 120 mJ, 10 Hz, SSP (50 mu s), E-SSP-A: 120 mJ,10 Hz, SSP+acid, E-VSP: 120 mJ, 10 Hz, VSP (100 mu s), E-VSP-A: 120 mJ, 10 Hz, VSP+acid, E-SP: 120 mJ, 10 Hz, SP (150 mu s), E-SP-A:120 mJ,10 Hz, SP+acid, E-LP:120 mJ,10 Hz, LP (300 mu s), E-LP-A:120 mJ,10 Hz, LP+acid; D-C: acid was applied and used as control, D-SSP: 80 mJ, 10 Hz, SSP, D-SSP-A: 80 mJ, 10 Hz, SSP+acid, D-VSP: 80 mJ, 10 Hz, VSP, D-VSP-A: 80 mJ, 10 Hz, VSP+acid, D-SP: 80 mJ, 10 Hz, SP, D-SP-A: 80 mJ, 10 Hz, SP+acid. After application of etch-and-rinse adhesive, composite built-ups were created with a nanoceramic composite. Specimens were sectioned into serial 1-mm(2) sticks, and mu TBS was measured in five sticks from each tooth randomly selected (n = 30). Failure modes were determined under a stereomicroscope. mu TBS test data were analyzed by Welch-ANOVA followed by Dunnett's T3 tests and failure mode distributions were analyzed by Pearson Chi-square test (p = 0.05). mu TBS was higher for enamel and dentin after additional acid etching than laser irradiation alone. E-SSP-A group exhibited the highest mu TBS for enamel (p < 0.05). The D-SP-A group showed the highest value but the difference was not significant in comparison to D-C (p > 0.05). The mu TBS of laser-irradiated but not acid-etched groups decreased when longer pulse durations were used. Laser treatment could enhance or impair the mu TBS to enamel and dentin depending on the pulse duration used and additional acid application.