Abstract: An apparatus for separating foreign bodies from a stream of fiber material includes a vertical chute having an upper inlet and a lower outlet; a mechanism for introducing the fiber material into the chute inlet; and a detector positioned in the chute for emitting a sensor signal upon passage of a foreign body. The fiber material is propelled from the detector towards the chute outlet substantially solely by gravity. The apparatus further has a waste discharge opening provided in the chute between the detector and the chute outlet; a deflecting mechanism arranged in the chute and having first and second positions. In the first position the deflecting mechanism causes the stream of fiber material to proceed in the chute to and through the chute outlet and in the second position the deflecting mechanism causes the stream of fiber material to proceed through the waste discharge opening.