Method and arrangement for processing a paper or board web (1) or similar fibre web, in which method a processing mixture is spread onto the surface of the web. hi the method, the web (1) to be processed is lead from a press nip (8) and pressed between rolls (8) in this nip. Before the web enters the nip, such an amount of processing mixture is spread onto at least one side of the web (1), that the processing mixture is still wet when it enters the nip.