Abstract: The implantable electrochemical sensor for amperometric measurements in body liquids comprises at least one measurement electrode formed as a platinum wire, a reference electrode tubularly surrounding the measurement electrode and possibly made up of several parts and made of stainless steel containing molybdenum as an alloying component. Furthermore, a layer of an immobilized enzyme, such as glucose oxidase, is disposed on the electrodes. The sensor is intended for use for the control of blood sugar and tissue sugar in diabetics and is suitable to be employed in a portable diagnostic and/or therapeutic apparatus.