A gripper for plastic containers adapted to be mounted on a transfer starwheel, said gripper comprising: - a telescopic arm defining a first longitudinal axis formed by a first rail, adapted to be fixed by means of a support to said transfer starwheel, and to rotate about a second axis (Y") perpendicular to said first longitudinal axis, and by a first slide, adapted to slide along said first longitudinal axis and provided with a free outer end, - two arms (91', 91") each having a first free end onto which a respective jaw (90', 90", 90a, 90b) is bolted and a second end hinged by means of a pin to the free end of the first slide, said arms (91', 91 ") being adapted to assume a first extreme position, in which they are clamped onto each other by means of a return spring, and a second extreme position, in which they are separated from each other by rotating about the pins, said arms (91', 91") being each provided with a roller (93', 93") free to rotate about a respective third axis perpendicular to the longitudinal axis of the gripper, - a second slide, adapted to slide longitudinally along the first slide, and be wedged between the two rollers (93', 93"), thus separating the first free ends of the two arms (91', 91") and, thus the two jaws (90', 90"), from each other, characterized in that it includes: a first cam mechanism to make said telescopic arm rotate about the second axis (Y"), a second cam mechanism to make the first slide run on the first rail, said first slide having an inner end supported by the first rail during its movement, and a third cam mechanism to make the second slide run on the first slide. - a telescopic arm defining a first longitudinal axis formed by a first rail, adapted to be fixed by means of a support to said transfer starwheel, and to rotate about a second axis (Y") perpendicular to said first longitudinal axis, and by a first slide, adapted to slide along said first longitudinal axis and provided with a free outer end, - two arms (91', 91") each having a first free end onto which a respective jaw (90', 90", 90a, 90b) is bolted and a second end hinged by means of a pin to the free end of the first slide, said arms (91', 91 ") being adapted to assume a first extreme position, in which they are clamped onto each other by means of a return spring, and a second extreme position, in which they are separated from each other by rotating about the pins, said arms (91', 91") being each provided with a roller (93', 93") free to rotate about a respective third axis perpendicular to the longitudinal axis of the gripper, - a second slide, adapted to slide longitudinally along the first slide, and be wedged between the two rollers (93', 93"), thus separating the first free ends of the two arms (91', 91") and, thus the two jaws (90', 90"), from each other, characterized in that it includes: a first cam mechanism to make said telescopic arm rotate about the second axis (Y"), a second cam mechanism to make the first slide run on the first rail, said first slide having an inner end supported by the first rail during its movement, and a third cam mechanism to make the second slide run on the first slide. a first cam mechanism to make said telescopic arm rotate about the second axis (Y"), a second cam mechanism to make the first slide run on the first rail, said first slide having an inner end supported by the first rail during its movement, and a third cam mechanism to make the second slide run on the first slide.