A concealed hinge for rotatable moving a door, in particular a reinforced door, connected to a tubular support structure ( F, CF) which includes a rear counterframe anchored to a wall or a similar support and a front frame anchored to the counterframe, the hinge comprising a fixed member and a movable member being rotatably coupled thereto for rotating about a first longitudinal axis between an open position and a closed position; wherein said fixed member includes a box-shaped hinge body to be concealed within the tubular support structure ( F, CF), said movable member including a connecting plate anchorable to the door susceptible to extend from the tubular support structure ( F, CF) in said open position and to concealedly retract within the tubular support structure ( F, CF) in said closed position; wherein said box-shaped hinge body includes a pair of end seats ( 12, 12') defining said first axis, said connecting plate including a first central portion susceptible to be operatively connected with the door and a pair of second end portions ( 23, 23 ') facing each other and reciprocally operatively connected with the end seats ( 12, 12') of said hinge body, wherein said hinge body includes a longitudinal passing-through bore defining said first longitudinal axis to mutually connect said end seats ( 12, 12'), said movable member further includes a substantially cylindrical shaft inserted into said passing-through bore being provided; wherein said second end portions ( 23, 23') of said connecting plate include respective operative surfaces ( 27, 27') susceptible to remain faced to said end seats ( 12, 12') during use, the latter ( 12, 12') including a respective annular housing ( 14, 14') susceptible to house a respective anti-friction element ( 15, 15') of the hinge, said annular housings ( 14, 14') and the respective anti-friction elements ( 15, 15') being mutually configured so that the corresponding operating surfaces ( 27, 27') of the second end portions ( 23, 23') of said connecting plate faced to the respective end seats ( 12, 12') of said body are susceptible to come in contact engage with the respective anti-friction elements ( 15, 15'); characterized in that: - said first central portion of said connecting plate includes a first plate-shaped member defining a first plane ( π) substantially parallel to said first longitudinal axis, said second end portions ( 23, 23') including a pair of second plate-shaped members defining respective second planes ( π', π") substantially parallel to each other and perpendicular to said first plane ( π); - when the operating surfaces ( 27, 27') of the second end portions ( 23, 23') of said connecting plate come in contact engage with the respective anti-friction element ( 15, 15') they remain spaced apart from said body; - said cylindrical shaft has the opposite ends ( 25, 25') mutually connected with said second end portions ( 23, 23') of said connecting plate to unitary rotate with the latter, said shaft being inserted with minimum clearance into said passing-through bore so that the latter laterally supports the former; - said shaft has a height ( h 3) slightly greater than the distance ( d 1) between the upper faces of said anti-friction elements ( 15, 15') so that when one of the operative surfaces ( 27, 27') of the second end portions ( 23, 23') of said connecting plate come in contact engage with the respective anti-friction element ( 15, 15') the other operating surface ( 27, 27') remains spaced apart from the respective friction element ( 15, 15'); - said movable member further includes a mounting bracket having a first plate-shaped portion operatively fixable to the door and a second plate-shaped portion operatively connectable to said first central portion of said connecting plate. - said first central portion of said connecting plate includes a first plate-shaped member defining a first plane ( π) substantially parallel to said first longitudinal axis, said second end portions ( 23, 23') including a pair of second plate-shaped members defining respective second planes ( π', π") substantially parallel to each other and perpendicular to said first plane ( π); - when the operating surfaces ( 27, 27') of the second end portions ( 23, 23') of said connecting plate come in contact engage with the respective anti-friction element ( 15, 15') they remain spaced apart from said body; - said cylindrical shaft has the opposite ends ( 25, 25') mutually connected with said second end portions ( 23, 23') of said connecting plate to unitary rotate with the latter, said shaft being inserted with minimum clearance into said passing-through bore so that the latter laterally supports the former; - said shaft has a height ( h 3) slightly greater than the distance ( d 1) between the upper faces of said anti-friction elements ( 15, 15') so that when one of the operative surfaces ( 27, 27') of the second end portions ( 23, 23') of said connecting plate come in contact engage with the respective anti-friction element ( 15, 15') the other operating surface ( 27, 27') remains spaced apart from the respective friction element ( 15, 15'); - said movable member further includes a mounting bracket having a first plate-shaped portion operatively fixable to the door and a second plate-shaped portion operatively connectable to said first central portion of said connecting plate.