A safety syringe with a plunger in which a needle is attached to a mobile component that is mechanically not linked to the plunger but is slidable within the barrel of the syringe and has a valve mechanism for opening a port connecting the interior volume between the mobile component and the plunger to the needle bore. The mobile component is first pushed by the plunger to the bottom of the barrel so that the needle extends normally, the mobile component is mechanically locked in place for use conventionally, and the needle bore is opened. After use, the needle bore may be closed, the lock released, and the mobile component and attached needle sucked back into the barrel by pulling the plunger out, retracting the used needle into the barrel. There may be a plunger lock. There may be an upper barrel locking position for the mobile component.
