Arrangement for filling cassettes with fibres, characterized by the fact that it mainly consists of the combination of a supply magazine (1) for fibres; a pressing member (3) displaceable in said supply magazine (1) and actuating upon one side of the amount of fibres (2); in this supply magazine (1) second pressing members (9) actuating upon the second end of said amount of fibres (2); means that can control the said pressing member (3) or the both pressing members (3) and (9) in order to move the amount of fibres; separating means (6) capable of separating a well-determined amount from said amount; second separating means (12) that can co-operate with the aforesaid separating member (6) in order to further free or disentangle the entangled fibres of the separated part of fibres in the proper fibre supply magazine (1); means (17) able to remove the separated amount of fibres from the supply magazine (1) and a cassette (20) that can receive this small amount of fibres.