A fluid transfer system includes a Luer female connector having a main body containing an internal channel for passage of fluids and a collar surrounding at least a part of the end of the main body, and a Luer male connector having a main body with a longitudinal internal opening. The main body of the female connector contains a first threading on at least a part of the external surface of that portion that is surrounded by the collar, located at least in part facing an internal surface of the collar one of the ends of the main body of the Luer male connector contains a second threading on at least a part of its internal surface delineating the longitudinal internal opening, which engages into and fits in the first threading to ensure joining between the Luer male and female connectors.
