Apicoectomy is a surgical procedure that consists of radicular apex resection, eliminating periapical lesion. This study evaluated the effect of CO2 and Nd:YAG lasers on root dentine permeability after apicoectomy with Er:YAG laser. Forty-four single-rooted teeth, obtained from the Endodontic Laboratory stock from the Faculty of Dentistry of Ribeirao Preto, University of Sao Paulo, were used. The teeth were instrumented with the step-back technique, irrigated with 1.0% sodium hypochlorite and sealed with Sealer 26 (Dentsply, Brazil) and lateral condensation. The samples were divided into four groups of 11 teeth each that had the root sectioned 2mm from the apex: G1 - roots were sectioned with a 4138 diamond bur with cooling; G2 - roots were sectioned with pulsed Er:YAG laser at the following parameters: 15 Hz and 250 mJ; G3 - roots were sectioned with pulsed Er:YAG laser and Nd:YAG laser (10 Hz, 100 mJ, and 1 W) was app0lied on the sectioned surface; G4 - roots were sectioned with pulsed Er:YAG laser and CO2 laser (5 W, 10 seconds ON and 20 seconds OFF) was applied to the sectioned surface. The teeth were then impermeabilized with cyanoacrylate and placed in 0.5% methylene blue for 7 days. The proximal surface of the samples was removed for exposure of the sealed root canal and dye penetration was measured by means of microscopic evaluation. The results showed a statistically significant difference at the level of 1%. We conclude that all treatments presented microleakage and can placed in increasing order: Er:YAG (G2), Bur (G1), Er:YAG + Nd:YAG (G3); Er:YAG laser presented the lowest microleakage values, showing its viability for clinical use in apicoectomies.