Abstract: The present invention concerns a device in a chair (1), especially a chair with an adjustable back of the chair (2) and head rest (3), in that in between a section of the head rest (3) and an attachment section on the chair construction is arranged a connecting element (18) with for example a rod (17), which by movement of the adjustable back of the chair (2) is arranged to affect the angle of the head rest (3) in relation to the back of the chair (2), and for the purpose of giving instructions on a head rest that by simple means be uncoupled in a reclined position of the back of the chair, there is according to the invention proposed a groove (21), a blocking device (22) and a coupling organ (24) which come into effect in the reclined position of the back of the chair, either in a manual or automatic way.