A support for connecting a rear-view mirror to a vehicle, including on vehicles suitable for towing a trailer, includes a connecting device to the vehicle, a supporting device of the rear-view mirror, and a device to movably connect the supporting device to the vehicle, which connecting deice allows the supporting device to be moved to any position between a respective retracted position, with respect to the connection device, particularly in which the rear-view mirror is nearest to the vehicle, and a respective extended position, with respect to the same connecting device, particularly in which the same rear-view mirror is furthest from the same vehicle, wherein the connecting device has a plurality of pairs of surfaces for a slidable engagement to corresponding pairs of surfaces of the connecting device.