Indiana University-Purdue University Indianapolis (IUPUI) / Brasseler USA (Savannah, GA) developed and introduced a bioceramic putty called EndoSequence Root Repair Material (ERRM) that can be used as a retrofilling material for surgical endodontics. The material is said to have many of the same chemical, physical, and biological properties as mineral trioxide aggregate (MTA), but with superior handling characteristics. The material is composed of calcium silicates, monobasic calcium phosphate, zirconium oxide, tantalum oxide, proprietary fillers, and thickening agents. ERRM is said by the manufacturer to bond to adjacent dentin, have no shrinkage, be highly biocompatible, hydrophilic, radiopaque, and antibacterial due to a high pH during setting. Investigations on the sealing properties of this material have not yet been conducted. The purpose of this study was to compare the microbial leakage of Enterococcus faecalis in teeth with root-end fillings using ProRoot MTA and Brasseler’s ERRM in a dual-chamber bacterial leakage model as described by Torabinejad and colleagues. The aim of this investigation was to compare the bacterial microleakage of these two root-end filling materials exists. Sixty-two human, single-rooted, mandibular premolars in which extraction was indicated were accessed and instrumented in an orthograde fashion with hand and rotary files. Root resection of the apical 3 mm was then completed and root-end retropreparations were created for placement of root-end filling material. Twenty-seven of these premolars had root-end fillings using ProRoot MTA and 27 had root-end fillings using ERRM. Two teeth were used as a positive control group with no root-end filling, and two other teeth were used as a negative control group and were sealed and coated with dentin bonding agent. The teeth were then evaluated for microleakage using a dual-chamber bacterial microleakage model for 40 days as described by Torabinejad and colleagues. Microleakage was determined by the presence of turbidity in the lower chamber of the apparatus and was assessed each day. Fresh samples of E. faecalis were used every three days to inoculate the apparatus and serve as a bacterial challenge for the materials. Results were recorded every day for 30 days. The outcome of interest (bacterial turbidity) and time-to-leakage (in days) were determined for each of the samples. Survival analysis was used to compare the two groups with a Kaplan-Meier plot to visualize the results and a nonparametric log-rank test for the group comparison. The microleakage of ERRM was not statistically different (p > 0.05) than leakage of ProRoot MTA when subjected to E. faecalis over the 40 day observation period. Both groups had a small number of early failures (within 4 days) and no leakage was observed for the remaining 40 days of the study. Therefore, the null hypothesis was rejected. The results of this research support the use of either of these two materials when compared with the controls. The microleakage of Brasseler’s EndoSequence Root Repair Material was at least as good as ProRoot Mineral Trioxide Aggregate when tested with E. faecalis.