A robot system for use in surgical procedures has two movable arms each carried on a wheeled base with each arm having a six of degrees of freedom of movement and an end effector which can be rolled about its axis and an actuator which can slide along the axis for operating different tools adapted to be supported by the effector. Each end effector including optical force sensors for detecting forces applied to the tool by engagement with the part of the patient. A microscope is located at a position for viewing the part of the patient. The position of the tool tip can be digitized relative to fiducial markers visible in an MRI experiment. The workstation and control system has a pair of hand-controllers simultaneously manipulated by an operator to control movement of a respective one or both of the arms. The image from the microscope is displayed on a monitor in 2D and stereoscopically on a microscope viewer. A second MRI display shows an image of the part of the patient the real-time location of the tool. The robot is MRI compatible and can be configured to operate within a closed magnet bore. The arms are driven about vertical and horizontal axes by piezoelectric motors.