Abstract: Auto-non-reusable syringe-needle system for injections, for a single use, composed of a barrel (1) to contain the liquid to be injected, a piston (2) impelled by a plunger (3) to make it slide through the inside of the barrel (1), an internal rib or emergence (5) in the form of a ring and which emerges from the syringe-needle body between the front side of the completely introduced piston (2) and the tip of the canula (4) opposite to the bevel, which forms two fixed seats (6 and 7) on both of the valve for a moving body (8) located in the interior and coaxially movable and which has an elastic flexible circular emergence (9) which can act on the two seats (6 and 7) and which can go from a position whereby it allows movement in the direction of suction of the liquid, to a direction of injection, said moving body (8) having emergences (10) which serve as guides and which have channels (10) for the passage of the liquid.