Oral bacterial immunomodulators are based on inactivated or lysed pathogenic bacterial cells. The safety of these products for consumers critically depends on the effectiveness of procedures used for pathogen inactivation. In a market survey in Switzerland we tested 26 lots of three different immunomodulators for the presence of any remaining culturable cells. Dissolved stimulants were plated on Eugon agar for the unspecific cultivation of bacteria (including most of the pathogenic bacteria in the modulator) and on Chocolate+PolyViteX agar for the cultivation of Haemophilus influenzae. A total of 16 colonies were grown on either Eugon agar or Chocolate+PolyViteX agar. These colonies were characterized by amplifying and sequencing a 16S rDNA fragment using unspecific screening primers. None of the sequenced fragments could be associated with the inactivated or lysed pathogenic bacteria present in the modulator. These data indicate that the pathogen inactivation procedures used for all tested products are effective. They also demonstrate full compliance of all products with pharmacopoeial requirements regarding microbial purity. Finally, the spectrum of germs isolated confirms the notion that man is the primary source of microbial contamination in pharmaceutical products.