Background & Aim: The goal of many researchers conducted nowadays is to achieve adhesive materials that exhibit good bonding capability, simplified application and easy handling. In this regard, self - etching primer systems were introduced to the market. The aim of this study was to evaluate the micro- SHEAR bond strength of two new self - etching materials compared to an already established bonding materials. Methods & Materials: Sections of human third molars (1.5 mm) were used in this study. The tooth surfaces were polished with 600 grit SiC paper nder running water and randomly divided into three groups. In group I Clearfil Protect Bond (Kuraray Japan), in group II, Clearfil SE Bond (Kurary Japan) as control group, and in group ill, Clearfil Tri - S Bond (KUrary Japan) were used due to manufacturer's instruction. Hollow tygon tubes (0.7×0.5mm) were placed on the enamel and dentin surfaces and Clearfil AP-X composite was inserted into the tubes. After 40 seconds light curing, the tygon tubes were removed and samples were stored in distilled water for 24 hours. Micro – SHEAR bond strength was measured (EZ-test, Shimadzu Co., Kyoto, Japan) and the data was statistically analysis by one - way ANOVA and multiple comparison with LSD.Result: Mean bond strength in enamel was 35.76±6.89 mpa in group I; 33.62±5.59 mpa in group II, and 34.65±5.65 mpa in group III. Their difference was not statically significant. Mean bond strength in dentin was 34.47±6.0 mpa in group I, 45.20±10.3 mpa in group II, and 35.99±6.13 mpa in group III. The bond strength in group II was higher than group I and II (P<0.05), and the difference between group I and II was not statistically significant.Conclusion: After 24 hours, the SHEAR bond strength of two new adhesive systems to enamel was similar to SE Bond, however, SE Bond exhibited a higher bond strength to dentine.