Abstract: An ultrasound therapy probe is provided comprising a therapy transducer movably mounted on a probe body, an at least partially deformable flexible casing around the therapy transducer, and a guard ring limiting deformations of the flexible casing when the transducer moves with respect to the probe body. The therapy transducer can be moved between a therapy position and a retracted position, the guard ring constituting an end-of-travel stop against which the therapy transducer bears in a therapy position. This ensures that movements of the organ to be treated are kept to a minimum when the therapy transducer moves with respect to the probe body.