With the advent of transgenic technologies, the number of mice shipped around the world has increased exponentially.Whereas once standard inbred lines were obtained from a relatively small number of commercial suppliers, with one particular supplier producing a large number of mutant and congenic mice with a clearly defined and reliable health status, there are now requests from researchers to import genetically modified mice from a wide range of sources.Many of these sources are research facilities associated with universities or hospitals with all the associated fiscal restraints of academic institutions, rather than the large commercial suppliers that operate with different financial or management criteria.