It is now necessary to use only one instead of two of the several prescribed selective isolation agars (Oxford agar, PALCAM, LPM plus esculin and ferric iron, MOX). Oxford agar is still the preferred standard selective isolation medium. MOX has been added to the list of prescribed selective agars and LPM without added esculin and ferric iron has been removed. Trial use of the new chromogenic differential selective agars, like BCM, ALOA, CHROMagar Listeria and Rapid' L. mono, is encouraged as long as it is in parallel with one of the prescribed selective agars. The new agar media differentiate L. monocytogenes/L. ivanovii colonies from those of other Listeria spp. and will greatly facilitating picking of L. monocytogenes colonies when colonies of more than one species are present on a plate.