Disclosed herein is a system for navigated punction, biopsy or ablation comprising a mobile electromagnetic field generator for generating an electromagnetic navigation field which is connected to an apparatus for medical imaging, a needle-like instrument (16), comprising a sterile distal portion (22) and an optionally non-sterile proximal portion (20), a removable protection device (30) for encapsulating the sterile distal portion (22), a sensor (38) suitable for carrying out measurements allowing for determining the position of the sensor (38) within the navigation field, and a sensor carrier (26). The sensor carrier (26) comprises an elongate carrier body (36) having proximal and distal ends. The sensor (38) is attached to or enclosed by said carrier body (36) close to its distal end. A connection mechanism (32) is provided allowing to releasably connect said sensor carrier (36) with the non-sterile proximal portion (22) such that said elongate carrier body (36) extends from said connection position in distal direction.