A retractable barrier comprises a flexible element (2) which may be withdrawn from or retracted back into a cylindrical body (4). Body (4) houses a helical spring which is twisted as the element (2) is withdrawn. The energy stored in this twist is used to retract the withdrawn element on release. The element (2) which may be reflective and electrified in use is drawn out of the body through a gap (5) which extends along a major part of the axis of the cylindrical body. This provides a gate or in conjunction with other barriers an enclosure.