An adjustable retractable hinge for articulating a door to a fixed structure, comprising: - a first body, with a corresponding first containing housing, intended to be inserted within a corresponding first cavity obtained either in said fixed structure or in said door, - a second body, and a second containing housing, which houses said second body and which is intended to be embedded in a corresponding second cavity obtained either in said door or in said fixed structure, - three arms (52, 54, 56), shaped as a rocker and associated to said bodies (4, 6) so as to allow the rotation of the door with respect to said fixed structure, said three arms comprising two substantially equal outer arms (54,56), articulated to the first body and sliding along guides obtained in the second body, and a central arm, articulated to the second body and sliding along guides obtained in the first body, said second body comprising: - a central portion, facing said central arm and interposed between the outer arms (54,56), and provided with an element for fixing and adjusting said second body to said second containing housing, said element causing the movement of said second body in the direction of the either greater or lesser insertion depth in the corresponding second containing housing, - guiding means (21,24) for said movement of said second body in the direction of its insertion in the corresponding second containing housing, said guiding means (20, 21,24) being arranged symmetrically with respect to said adjustment element, the hinge being characterized in that: the second body is made in one piece, and in that the element is a single element for fixing and adjusting said second body to said second containing housing (10, wherein the single element works as a single fixing element of said second body to the corresponding containing housing. - a first body, with a corresponding first containing housing, intended to be inserted within a corresponding first cavity obtained either in said fixed structure or in said door, - a second body, and a second containing housing, which houses said second body and which is intended to be embedded in a corresponding second cavity obtained either in said door or in said fixed structure, - three arms (52, 54, 56), shaped as a rocker and associated to said bodies (4, 6) so as to allow the rotation of the door with respect to said fixed structure, said three arms comprising two substantially equal outer arms (54,56), articulated to the first body and sliding along guides obtained in the second body, and a central arm, articulated to the second body and sliding along guides obtained in the first body, - a central portion, facing said central arm and interposed between the outer arms (54,56), and provided with an element for fixing and adjusting said second body to said second containing housing, said element causing the movement of said second body in the direction of the either greater or lesser insertion depth in the corresponding second containing housing, - guiding means (21,24) for said movement of said second body in the direction of its insertion in the corresponding second containing housing, said guiding means (20, 21,24) being arranged symmetrically with respect to said adjustment element, the hinge being characterized in that: