We are developing haptic interfaces compatible with functional magnetic resonance imaging (fMRI) to study the brain mechanisms of motor control in humans. This paper describes the different phases of our project, examines the constraints and presents possible solutions. The constraints imposed by the harsh yet sensitive MR environment as well as the smooth and safe control required for interaction with human motion demand a novel robotic technology. Our concept is based on a hydrostatic masterslave system used to power the robot near the scanner from outside the shielded MR room. Force/torque and position sensors measure the de ection of an elastic polymer probe via light intensity measurement over ber optics, thus allowing all electronic components to be placed outside the MR room. This concept was validated through two interfaces able to provide force and motion feedback simultaneously with imaging.