A method for processing a carcass part of slaughtered poultry, which carcass part includes bone parts with at least a part of the rib cage, at least a part of the breast fillet, other muscle tissue that does not form part of the breast fillet, for example at least a part of the back meat that is naturally present on the rib cage and the spine and/or at least a part of the abdominal muscle tissue. This method includes the steps of making an incision through the meat at least up to the bone parts lying under the meat, which incision is made in an area between the breast fillet and the other muscle tissue that does not form part of the breast fillet, and which incision in that area substantially follows the shape of the breast fillet, and detaching the breast fillet from the bone parts of the carcass part.