This study determined the shear bond strength (SBS) of composite bonded to chlorhexidine-treated enamel and untreated enamel. Fifty human molars were mounted in cold- cure acrylic and the superficial enamel of the buccal or lingual surface was exposed using 600-grit silicon carbide paper. During the experimental protocol, the control group (n = 25) and the experimental group (n = 25) were stored in distilled water at 37 degrees C. The experimental group was immersed in 0.12% chlorhexidine gluconate for 1 minute, 4 times daily, for 7 days. Prisma APH composite was then bonded to all samples following acid etching for 30 seconds, and the SBS was determined. Shear bond strengths for the control (13.23 +/- 3.22 MPa) and the experimental (13.67 +/- 4.59 MPa) groups were not significantly different using a t-test. The result may be attributed to either a lack of effect of chlorhexidine or to the acid etch which dissolves the affected superficial enamel leaving an unaffected substrate for bonding.