Abstract: Press for the injection-moulding of plastic materials and/or non-ferrous alloys comprising a movable plane and a fixed plane, on whose opposite sides a mould and a counter mould are applied. Four cross members are provided associated to said movable (10) and fixed (12) planes and clamping means (46) acting on said cross members (14) in order to transmit the pressure generated by a piston means to said movable plane (10) during the injection phase. The cross members (14) are, at one end, integral with the movable plane (10) and project from this on the side of the fixed plane (12), four operating heads (28), each of them comprising one of said piston means for controlling the closing of the mould and counter mould and one of said clamping means (46).