Abstract: An insertion device for the introduction of a medical implement, the insertion device including a hollow body, a needle holder mounting portion, a needle holder, a needle adapted for a medical implement to be mounted therewith relative to the needle, biasing means to bias the needle and the needle holder into the hollow body, and a retaining mechanism adapted to at least temporarily retain the needle and the needle holder in a forward condition in which the needle extends forward of the hollow body against the biasing force of the biasing means. The retaining mechanism of the insertion device retains the needle and the needle holder in the forward condition until the medical implement is disassociated from the retaining mechanism and unless the retaining mechanism is operated independently to retain the needle holder and the needle in the forward condition.