Purpose: To investigate whether the application of chlorhexidine in a two-step self-etching adhesive has an adverse effect on the immediate resin-dentin bond strength. Materials and Methods: Different amounts of 20 wt% chlorhexidine digluconate were added directly to the Clearfil SE Bond primer to prepare mixtures of 4 different concentrations of chlorhexidine: 0.05 wt%, 0.1 wt%, 0.5 wt%, and 1.0 wt%. Sixteen extracted third molars were randomly divided into 4 groups. Each group corresponded to one of the 4 chlorhexidine concentrations. Each of the 16 teeth was sectioned into halves. One half was customarily bonded with Clearfil SE Bond without chlorhexidine, and the other half was bonded with Clearfil SE Bond containing different concentrations of chlorhexidine. Microtensile bond strengths were tested immediately after specimen preparation. The modes of fractures were examined under a stereomicroscope. Results: No significant difference of immediate resin-dentin bond strength was observed between the control groups and any of the experimental groups containing chlorhexidine (p > 0.05). Conclusion: The addition of chlorhexidine to a two-step self-etching adhesive primer (Clearfil SE Bond primer) has no adverse effect on the immediate resin-dentin bond strength when the chlorhexidine concentration in the primer is lower than or equal to 1.0 wt%. Schlagwörter: chlorhexidine, bond degradation, matrix metalloproteinases, self-etching adhesives, microtensile bond test