Aim: to evaluate the effect of using two different mouthwashes, either chlorohexidine or neem-based, on microtensile bond strength of resin composite bonded to deep dentin. Materials and Methods: Twenty four intact freshly extracted human mandibular molars were selected for this study. All selected teeth were placed in acrylic blocks, then cross-sectioned horizontally leaving a flat deep dentin surface. Bonding protocol was applied to all teeth following the manufactures' instructions, followed by application of resin composite to the exposed dentin. All teeth were randomly assigned into three equal groups (n=8) according to the mouthwash used for immersion. Group (1): teeth were immersed in distilled water for 12 hours (Control group), Group (2): immersion was in Chlorhexidine mouthwash for 12 hours and Group (3): immersion was in Neem (Azadirachata indica) mouthwash for 12 hours. Microtensile bond strength was evaluated after the immersion time using a universal testing machine. Results: One-way ANOVA test revealed no statistically significant difference among the groups tested (p-value = 0.377). Conclusions: various mouthwashes, used in this study, had no effect on microtensile bond strength of resin composite to deep dentin.