|In a time of 10 years, 428 voice prostheses with a mean life time of 162 days were used. In the microbiological examination the dominating bacteria were S. aureus, Klebsiella sp. and Proteus sp. In addition C. albicans, C. glabrata, C. krusei and C. tropicalis were the main fungi on the silicone surface. The diversity of bacteria and fungi species showed a level of saturation on the surface which was higher on ESKA-Herrmann prostheses. This is caused by the limited space on the silicone prostheses. Thereby a more frequent colonisation with C. krusei on ESKA-Herrmann prostheses was measured.