This study evaluated in vitro the external temperature increase at the three root thirds using five different fiber optic tip withdrawal techniques in 50 human canines. Er:YAG laser was applied with a 50/28 fiber optic tip with 250 mJ input, 112 mJ output, 10 Hz, 1 mm from the apical foramen: group 1: each third was irradiated starting at the apex for 1 s on each wall, with the irradiation turned off between thirds; group 2: apical third irradiated without movement for 2 s and tip withdrawn with continuous radiation up to the cervical third; group 3: tip activated at the apex and removed to the canal entrance in a straight line; group 4: tip activated at the apex and removed to the canal entrance with circular movements touching all walls; group 5: tip activated at the apex and removed to the canal entrance with clockwise circular movements for 6 s and then reinserting and removing with counterclockwise circular movements for another 6 s, touching all walls. Group 1 had significantly lower external temperature ( p<0.01). The middle third had the greatest temperature increase ( p<0.01). We conclude that the withdrawal techniques caused an increase in external root temperature that would not damage adjacent tissues.