An adjustable hinge for doors or windows is described. The adjustable hinge has hinge elements, a tubular cover, a plug and a wall. The hinge elements connect to a fixed frame of a door or a window and mobile frame of the door or the window. The hinge elements are pivotally connected through a pin that is engaged in a housing formed inside the hinge elements. The tubular cover covers the hinge elements which are associated with a locking means. The plug has a channel and is used to engage the housing of the hinge elements with the locking means. The adjustable hinge can also be transversally adjustable.