A valve connector for medical infusion lines including an external tubular body with an inlet end and an outlet end, an internal hollow spike and an intermediate sealing member including a head with pre-slit and an elastic hollow element formed with fluid-tight members in contact with the hollow spike and with an elastic thrust means, which tends to maintain the elastic head in a closed condition. The elastic thrust means comprises a base part joined to the elastic hollow element of the sealing member through a generally transverse annular wall, which, during axial displacement of the elastic head from the closed condition to the open condition, bends within an annular chamber defined between the base part and a portion with conical surface of the hollow spike.