Abstract: The pathway to the maxillary sinus is anatomically curved and narrow. Thus, the conventional approach using a straight endoscope and surgical tools is difficult to diagnose and treat some blind regions of the maxillary sinus through the nostrils. Such cases are usually dealt with by an approach with an external incision that causes large invasive surgery. In order to approach the blind regions without any external incision, a new bendable device and an image-guided robotic approach for the maxillary sinus surgery are required. This work reports design, development, and validation of an image-guided dual master-slave robotic system for the maxillary sinus surgery. Initially, specifications of the robotic system for sinus surgery are decided by analysis of the anatomical structure of the sinus. A method for determining the design parameters of continuum type salve robot is also presented. Based on the specifications and the design parameter determining method, a compact design of bendable dual slave robotic system for inspection and biopsy operation of the maxillary sinus area is devised and workspace analysis for verifying the robot design is conducted. The performance of the dual master-slave system equipped with flexible devices is validated through several phantom tests. The results suggest that bendable end-effectors and navigation software are useful to navigate and treat blind regions inside general sinus areas as well as the maxillary sinus.