The apical seal afforded by laterally condensed or thermomechanically compacted gutta-percha has been investigated. The present study measured apical leakage to a dye in roots filled by a combination of the two techniques (hybrid technique). The canals of 40 extracted teeth were endodontically prepared and separated into two equal groups. Lateral condensation with sealer was used in one group. The roots of the second one were filled using the hybrid technique. After immersion in Procion brilliant green, the roots were cleared for measuring the depth of penetration of the dye. The roots filled with the hybrid technique leaked significantly less (p<0.05) than the lateral condensation group (0.1 versus 0.475 mm mean penetration).