The invention relates to a method for processing poultry or a part thereof in a processing line, including the step of detaching and/or collecting a cartilage of the poultry's keel bone, whereby during transport of the poultry's carcass in the processing line, a cut is made in the cartilage of the keel bone. The cut is made initially transverse to the transport direction of the poultry and towards the poultry's backbone. The cut develops from the transverse direction to eventually a direction opposed to the transport direction.