The best known clinical picture of a one-sided necrotisising, infectious tonsillitis is the by Plaut and Vincent (1894) described angina Plaut-Vincent. In addition to this fusospirochetosis it is in case of necrotisising inflammations in the oropharynx differential-diagnostically important to consider also the anaerobic type Prevotella, especially Prevotella disiens as a potential trigger . Because the clinical course forms of a necrotisising oropharyngeal inflammations can be very different and complicate so a suitable diagnosis, it is very important to get a complete and perfect cause proof. For getting this proof a correct test production, transport and cultivation are of extreme importance . The type Prevotella consists of different species gram-negative, obligate anaerobic strains. They are regarded as a cause of suppurating inflammations and abscesses of the genital tract and are components of the aerobic anaerobic mixed flora in case of gingival infections. The sole proof in the microbiological culture as a smear test result of a one-sided necrotisising tonsillitis has to be seen as a first description by reason of missing literature . As triggers for one-sided necrotisising tonsillitis are considered different causes. Next a carcinoma of the tonsil, Lues, Angina Plaut-Vincent have to be excluded. An infection with Prevotella disiens is an extremely rare variation in contrast. However, the transmission is possible by insufficient hygiene, lack phenomena and sexual intercourse and to consider therefore as an exclusion diagnosis.