A method, system and network element for tracing signaling messages related to a subscriber in a mobile communication system. In the solution according to the invention a functional entity of the mobile communication system receives a trace command which indicates the tracer and identifies at least one subscriber whose signaling messages are to be traced, and tracing is started, tracing comprising the steps of: copying the signaling message in response to reception or transmission of a signaling message related to the subscriber to be traced, and sending a copy to the tracer.