Abstract: An ultrasonic probe is adapted to be implanted in a human or animal body in contact with a wall of an organ to allow exploration of the organ by ultrasonics, inter alia by the Doppler effect. It comprises a support for a piezo-electric transmitter/receiver transducer, and a cover which covers the transducer and at least that part of the support which is remote from the organ. The transmitting/receiving surface of the transducer is in contact with a surface of the support, which is interposed between the transducer means and the organ. The probe also has conductors attached to the transducer extending to the outside of the body to carry the information transmitted/received by the probe. The support and the cover have a configuration and shape such as to allow the probe to be removed from the body without a complex surgical operation, particularly by simply pulling from outside on the connecting means.