An introducer sheath (110) has a tubular structure (140) that is expandable and contractible to a desired diameter. In a first configuration, the tubular structure (140) has a first diameter and a first axial length. In a second configuration, the tubular structure (140) has a larger second diameter and a shorter second axial length. An actuator includes an inner member (148) and an outer member (144). In response to relative movement between the members and the tubular structure (140) in a first or second direction, the actuator allows the tubular structure (140) to move between the first or second configurations. The tubular structure (140) can be a braided structure. The members can form an everted tubular sleeve. A proximal end of the outer sleeve can be movable relative to a proximal end of the inner sleeve. A locking system can fix the introducer sheath at a desired diameter.
