The aim of this study was to evaluate the bond strength of fiber posts luted with a one-step self-etching adhesive with the push-out test after phosphoric acid conditioning of the root dentin. Thirty-six single-rooted teeth were endodontically treated. Teeth were sectioned perpendicularly to the cementoenamel junction, and a 10-mm post space was prepared with a calibrated bur. Specimens were then divided into three groups according to the adhesive protocol: A, total-etch three steps; B, self-etch one step; and C, 32% phosphoric acid conditioning and self-etch one step. Fiber posts were luted with self-curing resinbased cement. Teeth were cut in 1-mm slices and pushed until failure with an Instron machine. Results were statistically analyzed with the ANOVA and Bonferroni tests (P .05). Two additional specimens from each group were examined under the scanning electron microscope (SEM). The 32% phosphoric acid significantly influenced the push-out bond strength of fiber posts luted with self-etch adhesives (P .05). SEM analysis showed a continuous hybrid layer with resin tags and lateral branches in groups A and C, while group B showed smear layer dissolution with poor infiltration of the tubules. Keywords: bond strength, fiber post, phosphoric acid, push-out, self-etch