A biological analysis system comprising at least one inlet and one outlet, at least two biological analysis devices connected to one another by a conveyor defining a closed circuit, each biological analysis device comprising a region for the exchange of tube holding racks with the conveyor. The conveyor and the at least one inlet of the biological analysis system comprise a reader of an identifier of a tube holding rack which reader is designed to communicate an identifier it has read to a controller of the biological analysis system, which controller is designed to apply a specific treatment to a tube holding rack identified by the reader of the conveyor and the identifier of which has not previously been read by the reader of the at least one inlet of the biological analysis system.