The purpose of this study was to evaluate the resin bonding to dentin irradiated by an Er: YAG laser. The bond strength of a light-cured adhesive resin to dentin irradiated at 126mJ was measured with the micro-tensile bond test. Scanning electron microscopy was used to investigate the bonded interfaces and the morphological changes to irradiated dentin caused by 37% phosphoric acid etching. The irradiated dentin exhibited bond strengths comparable to those of cut-dentin, with or without acid etching. The irradiated dentin surfaces were free of smears and plugs, and the dentinal tubules were open. Additionally, phosphoric acid etching demineralized the irradiated surface slightly, leaving a rough intertubular dentin surface and substantial amount of peritubular dentin. The Er: YAG laser affected not only the dentin surface, but also the subsurface. The laser irradiation increased the acid resistance of the peritubular dentin.