Abstract: Culture media for microorganisms containing blood or hemin, particularly Trypticase Soy Agar with blood, and chocolate agar, are combined with known chromogenic substrates to produce chromogenic media. Methods for preparing these chromogenic media include adding chromogenic substrates to the surface of previously prepared media, or incorporating the chromogenic substrate into the media as it is prepared. Methods for distinguishing microorganisms in a sample using these culture media are also described.