Introduction: Tubular penetration and adaptation of the sealer can determine the sealability of the root filling. The aim of this study was to assess, in vitro, the tubular adaptation and penetration depth and the adaptation to the root canal walls in the apical, middle, and coronal third of the root canal of five different sealers used in combination with softened gutta-percha cones. Methods: Fifty-two single-rooted teeth were prepared and filled with five different sealers and softened gutta-percha cones. Thereafter, the roots were cross-sectioned and prepared for scanning electron microscopic evaluation. Adaptation of the sealer to the root canal and tubular walls and tubular penetration were assessed. Results: AH Plus (Dentsply De Trey, Konstanz, Germany), an epoxy resin sealer, showed the best tubular adaptation and penetration. Conclusions: The tubular penetration and adaptation varies with the different physical and chemical properties of the sealers used. AH Plus showed the most optimal tubular penetration and adaptation to the root canal wall of the sealers tested. (J Endod 2011;-:1–4)