This study aimed to evaluate the effect of post space treatment protocol on the retention of fiber-reinforced post using two different luting agent, namely resin modified glass-ionomer and adhesive resin cement.Subjects and MethodsTo conduct this study, forty eight mandibular premolars were obtained. The samples were endodontically instrumented with crown down technique using Protaper rotary system before obturation.The crowns were sectioned transversally 2 mm above cement-enamel junction before embedding the roots in acrylic resin blocks.ResultsThe samples were divided into four groups (n=12) according to the type of irrigant used after post space preparation: distilled water, 37% phosphoric acid etchant, 5.25% NaOCl followed by 17% EDTA, and BioPure MTAD.Two samples from each group were examined using SEM to observe the effect of each irrigant.Each group was further subdivided into two subgroups (n=5) according to the type of the luting agent. The retention values of the luted fiber-reinforced posts were tested using pull-out test.Two samples from each subgroup were examined using SEM to detect the mode of failure.