A valve connector for medical infusion lines includes an external tubular body with an inlet end and an outlet end, a hollow internal pin and an intermediate elastic sealing member 3 having a head with pre-slotting and an elastic hollow element abutted radially against the hollow pin. The hollow pin has a closed terminal shaped, as a result of the insertion of a fluid introducer into the inlet end, in such a way as to make the elastic head assume an elastically deformed configuration without crossing the pre-slotting, which is opened to place in communication the inlet end with the outlet end through lateral holes of the hollow pin.