Abstract: A system for monitoring blood pressure within a blood vessel of a living being. The system includes an implantable sensor unit and an associated externally located energy application transceiver. The sensor unit is in the form of a housing including a movable deflection member and a tuned circuit including an inductor coil and a capacitor. The housing surrounds the wall of the blood vessel and includes a wall portion arranged to flatten a portion of the periphery of the blood vessel. The deflection member extends through a slot in the wall portion of the housing for engagement with only the flattened portion of the blood vessel to move in response to the pressure applied to the flattened portion of the blood vessel by the blood. The deflection member includes a ferrite core. The ferrite core is arranged to move with respect to the coil in response to the movement of the deflection member, thereby changing the inductance of the tuned circuit.