Abstract: A disposable self-locking injection site can be clamped onto tubing anywhere along the line. The injection site includes a tubular barrel having two sections integrally hinged together with snap-fitting coupler parts which lock the sections together in a closed position about the line. The tubular barrel is shaped to define an interior recess communicating with at least one needle-receiving aperture. The interior recess snugly receives a self-sealing needle-penetrable resilient member or sleeve for cushioning and fluidly sealing the line so as to permit fluid-tight injection and withdrawal of a needle.