This study evaluated the effects of irrigating solutions containing 5% boric acid + 1% citric acid or 1% peracetic acid + high concentration hydrogen peroxide on root cleaning and bond strength of cementation systems after 24 h and 6 months of glass fiber post cementation. One hundred and twenty roots were endodontically treated. The specimens were randomized into one of four treatments (n = 10): DW (distilled water); NaOCl2.5% + EDTA(17%) (2.5% sodium hypochlorite solution + 17% EDTA); PA(1%) + HP (1% peracetic acid solution + high concentration of hydrogen peroxide); BA(5%) + CA(1%) (5% boric acid associated with 1% citric acid). The cleaning efficacy in the cervical, middle, and apical thirds of the post-space, and the push-out bond strength at 24 h and 6 months after post cementation were evaluated by Kruskal-Wallis and two-way ANOVA tests, respectively. BA(5%) + CA(1%) showed statistically significantly superior cleaning efficacy compared to the other solutions. This irrigation protocol also resulted in higher bond strength at 24 h and 6 months, regardless of the root third considered, and this was statistically significantly higher than those seen for DW and PA(1%) + HP. For BA(5%) + CA(1%) irrigation protocol, type 1 adhesive failure was the most prevalent. Post-space irrigation with BA(5%) + CA(1%) provided both higher cleaning efficacy and better bond strength.