Objective: This study evaluated the effect of CPP-ACP treatment on the microtensile bond strength of 4 adhesive systems to enamel. Materials and methods: Forty extracted human molars were sectioned mesio-distally into 2 parts. The samples were randomly divided into experiment and control groups. In the experiment group, 1 mm thickness of CPP-ACP was applied to enamel using the brush before bonding to resin composite, using 4 bonding systems: Optibond Fl, Clearfil SE bond, Adper Single Bond 2, and Optibond all-in-one. In control group, the enamel did not receive CPP-ACP before bonding to resin composite, using the same bonding systems as experiment group. Following light curing of the adhesive, the resin composite was placed in increments. All specimens were stored in distill water at 37oC for 24 hours. The microtensile bond strength was measured using a universal testing machine. Data were analyzed by two-way ANOVA followed by Tukey's multiple comparison tests. Results: Microtensile bond strength of CPP-ACP-treated enamel using Optibond Fl (62.54+16.12), Clearfil SE bond (35.72+8.42), and Adper Single Bond 2 (18.27+6.38) group, did not have statistically significant difference compared to enamel that did not received CPP-ACP using Optibond Fl (56.03+10.16), Clearfil SE bond (30.97+7.72), and Adper Single Bond 2 (19.54+4.40) group. However, for Optibond all-in–one group, teeth received CPP-ACP (26.29+8.37) have significantly more microtensile bond strength than teeth that did not received CPP-ACP (9.78+4.52). Conclusion: CPP-ACP did not have effect on microtensile bond strength of Optibond Fl, Clearfil SE bond, and Adper Single Bond 2 to enamel. However, CPP-ACP increased microtensile bond strength of Optibond All-in-one to enamel.