A needle electrode (1) comprising a base element (4), a needle element (3) mounted on said base element and connection means (5) for connecting said needle element to external electronic equipment. The needle electrode further comprises a cover element (2) which is displaceable between at least two positions: an “active” position where the tip of the needle element (3) is exposed and a “secure” position where the tip of the needle element (3) is hidden within the cover element (2). In this way, the needle electrode (1) is provided with a shield (2) whereby the needle element (3) can be shielded after use whereby the user of the needle electrode (1) is protected from infection. A method of using a needle electrode (1) is also presented. An adjustable length needle electrode (80) is also presented.