Introduction: the object of this research was to evaluate the microshearing strength of two self-etching adhesives: one-step and two-step on enamel, upon acid and microsandblasting. Methods: 40 recently pulled human third molars, which were filed down with 600 - 2500 and divided into two groups: 1) one step (n = 20); 2) two steps (n = 20); then they were divided into four subgroups, following the procedures (sa-sm: adhesive application according to the manufacturer; sa-m: upon microsandblasting and adhesive application; ca-sm: 37% phosphoric acid application and adhesive application; ca-m: microsandblasting, 37% phosphoric acid and adhesive). Then, three layers of tygon were applied on each surface. Microshearing test conducted. The data were analyzed with the D’Agostino normality test. Afterwards, the two-criteria Anova analysis was conducted and Bonferrini postest (α = 0.05). Results: for the two-step adhesive prior application of 37% phosphoric acid and/ or microsandblasting, there is no significant increase in the enamel adhesion strength values (p = 0,678). The application of 37% phosphoric acid on enamel before the one-step adhesive increases the strength values (p = 0,001). Conclusions: microsandblasting before the adhesive process does not help increase the enamel adhesion strength values; the application of phosphoric acid helps increase the enamel adhesion strength values.