The invention relates to a method for marking at least one component of a multiplexed signal which is organised in the form of a successive transport packets and carries out a plurality of services each of which comprises at least one component, each of which is identified by a packet identifier in said transport packets, wherein each of said packets comprises a heading (20) and a data field (21). The inventive marking method comprises one step for inserting at least one particular transport packet, referred to as marking packet, which comprises only an adaptation field in the heading (20) thereof, into said multiplexed signal, wherein said marking packet is provided with the same packet identifier as the component to be marked and transports at least one marking information item of said component in the adaptation field.