The publication summarizes the present state in the diagnostic of periodontal pathogens. It discus-ses main advantages and pitfalls in classical cultivation methods and new DNAtechniques. In the recent methods of molecular diagnostics the method of hybridization in situ is described in more detail. Its basis, various variant procedures and possibilities are explained including specific examples of the use the detection of periodontal pat¬hogens.

        Key words: periodontal pathogens — anaerobic microorganisms — molecular diagnostics — hybridization in situ