Background: In this article, a medical robotic system that performs magnetic resonance imaging-guided focused ultrasound surgery ablation is presented. The main innovation of this robotic system is that all the actuators are placed outside the water container. The transducer is immersed in water through an arm which is attached to the angular stage. Materials and Methods: The system includes three linear and one angular stage. The device uses piezoelectric motors for each motion stage. The accuracy was achieved with optical encoders. A focused transducer operated at 1 MHz with a radius of curvature of 10 cm and a diameter of 4 cm was used. A polyacrylamide gel was used to assess the ultrasound protocol. Results: The system was tested in the magnetic resonance imaging (MRI) environment and was proved to be a magnetic resonance compatible. The accuracy of the system was tested, and it was found that spatial steps of 0.2 mm can be safely and reliably achieved. With this robotic system, it is possible to access many organs that ultrasound penetrates with the patient placed in a prone position. Conclusion: The proposed robotic system can be modified so that it can be used for other applications. One example of an alternative application is MRI-guided biopsy. Another application is to replace the transducer arm with a radio frequency (RF) device to perform MRI guided RF ablation. Finally, the maneuverability of the robotic system can be enhanced further by attaching another angular stage to the system.