Objective: The purpose of the present study was to compare ethylenediaminetetraacetic acid conditioning and phosphoric acid conditioning of dentin in combination with two principally different commercial dentin bonding systems. Method and materials: Twenty-one extracted human third molars were used. All teeth were caries free, and no teeth were root filled. In total, 29 pairs of dentin surfaces were obtained from 21 teeth. One dentin surface in each pair was etched with a 32% phosphoric acid gel for 15 seconds, and the opposite surface was etched with a 24% ethylenediaminetetraacetic acid gel for 3 minutes. One experimental group of 15 dentin surface pairs was subsequently bonded with All-Bond 2, a two-component system, and the other group of 14 pairs was bonded with Prime & Bond NT, a one-bottle adhesive. A flowable resin composite was inserted in the experimental cavity and light cured. Shear bond strength testing was performed according to the protocol of the International Organization for Standardization. Results: The combination of conditioning with ethylenediaminetetraacetic acid and bonding with All-Bond 2 was significantly better than all other combinations, providing a shear bond strength that was 61% to 123% greater. Conclusion: Use of ethylenediaminetetraacetic acid in combination with All-Bond 2 resulted in a significantly greater bond strength to dentin than did conventional acid etching.