High density optical fiber distribution sub-rack comprising: a chassis for housing a plurality of shelves, the chassis comprising at least two shelf storage areas placed side by side with each other, at least one shelf housed in one of the at least two storage areas of the chassis, the at least one shelf having an internal hollow seat for connection modules, the at least one shelf comprising one or more connection modules having a plurality of adapters for interconnection optical fibers, the connection modules being arranged in the internal hollow seat of the at least one shelf at the frontal face of the at least one shelf, wherein the at least one shelf is guided so as to be movable towards the external of the chassis by the succession of a translation movement and a rotation movement of the at least one shelf.