Objective: The aim of this in vitro study was to investigate the effect of nanopropolis and nanochitozan on the microtensile bond strength (μTBS) of universal adhesive to dentin. Materials and methods: Fifteen extracted sound human permanent molars were selected. Occlusal one-third of the tooth crowns was removed to expose the mid-coronal dentin. The teeth were randomly divided into three equal groups according to the pretreatment before application of the adhesive i.e. Group A: 1% nanochitozan was applied, group B: 1% nanopropolis was applied and group C: received no treatment (control). Universal adhesive Prime & BondTM was applied in the self- etch mode according to manufacturer's instructions. Composite build-ups were done using a specially fabricated split Teflon mold. After being kept in an incubator at 37°C for 24 hours, Teeth were sectioned to obtain beams with cross-sectional areas of about 1 mm × 1 mm. μTBS test was done using universal testing machine. One-way ANOVA followed by Tukey post hoc test were used to compare between more than two groups in non-related samples. Results: A statistically significant difference was found between (Group B) and each of (Group A) and (Group C) where (p=0.001). No statistically significant difference was found between (Group A) and (Group C) where (p=0.115). Conclusion: Within the limitations of this study it could be concluded that, nanopropolis (conc 1%) enhance the immediate μTBS of Prime & BondTM universal adhesive to dentin. Nanochitozan (conc 1%) did not improve the μTBS of Prime & Bond TM universal adhesive to dentin.