Background;The smear layer is considered an obstacle limiting the penetration of adhesive types of cement into the dentinal tubules, thus adversely affecting the bond strength of the fiber posts. Objective;The purpose of this study was to assess the effect of ultra-sonic activation on the bond strength of fiber posts, cemented with self-adhesive cement to the root dentin.Methods; A total of 18 recently extracted single rooted premolars were selected. The root canals were prepared using ProTaper rotary, samples were obturated with Protaper universal gutta percha points. Post space was prepared using gates glidden drills, specimens were randomly divided into two groups of n=9 according to the irrigation application techniques; Group 1: conventional syringe, Group 2: ultra-sonic activation. Posts were cemented using Rely X Unicem2, bond strength was determined by pull out test.Results; A statistically significant higher mean value was recorded in Group 2 compared to Group 1.Conclusions; Ultrasonic activation can aid the irrigation with 2.6% NaOCl followed by 17% EDTA in smear layer removal, contributing in a triad way of cleaning of the root canal system and thus promoting the bond strength of fiber posts.