AIM The aim of this study is to evaluate the sealing ability of Biodentine(TM), which is new calcium-silicate based dental cement and has endodontic indications similar to those of MTA. METHODS The study sample consists of 21extracted human mandibular anterior teeth. The teeth were submitted to root-end preparation and instrumented up to file #40 by step back technique and randomly divided into 3 study groups (n=7): White MTA Angelus(TM) (Angelus, Angelus Odontológica, Londrina, PR, Brazil), Biodentine(TM) (Septodont, SeptodontSpecialités, Saint-MaurdesFosses, France) and the controls. The length of dye penetration between the filling material and tooth structure was measured in millimetres, using a calibrated stereo microscope (Leica MZ75, Germany) at 20× magnification under the same conditions. One-way Analysis of Variance (ANOVA) was used to indicate differences between the experimental groups and the controls. In addition, Tukey Multiple Comparisons Test was used to indicate differences within each group. RESULTS The results showed that none of the groups were completely sealed. The mean and standard deviation for dye penetration in Biodentine(TM) group was 0.63±0.20 and in MTA Angelus(TM) group, it was 0.26±0.25. Regarding the comparisons between each group, significant differences were not observed (P=0.0193). The comparison between materials only found a significant difference only between MTA Angelus(TM) and Biodentine(TM) (P<0.05). CONCLUSIONS This study evaluated the possibility of Biodentine(TM)'s sealing ability and marginal adaptation, since no studies are available on Biodentine. However, further in vitro and in vivo investigations should be conducted to determine the suitability of Biodentine(TM) for clinical application.