Purpose: This study was designed to compare marginal adaptation of MTA and Endosequence Root Repair Material (ERRM) as retrograde filling materials. Materials and methods: 40 maxillary anterior teeth were prepared and obturated with gutta-percha and AH plus using lateral compaction technique. Apical 3mm of the roots were resected and retrograde cavities were prepared with diamond coated ultrasonic retrotip. Teeth were divided randomly into two main groups (I,II) according to blood contamination of retrograde cavities and every group then divided into two sub-groups (A,B) according to retrograde materials (MTA,ERRM). Teeth sectioned longitudinally and examined for marginal gap using SEM. Results: revealed that the high mean value in cavities without blood contamination and filled with MTA in group I and the high mean value in cavities smeed with blood contamination and filled with MTA in group II. There was no statistically significant difference between 4 groups. Conclusion: MTA and ERRM exhibited nearly comparable marginal adaptation in dry or blood environment.