Introduction: New studies show, that SRB are associated with periodontaldisease. We could identify in a pilot study, that 90% of isolated SRB aremember of the new species Desulfomicrobium oraleb(Langendijk et al., 2001),whereas Desulfovibrio fairfieldensis oral was infrequent detected. The aimof our study is the detection of these two SRB strains as a part of themicrobiologic periodontal diagnostics using quantitive PCR. Material and method: 15 patients undergoing Supportive Periodontal Treatment (SPT)participated in this study, who got before a complex periodontal therapy.After the baseline examination a supportive periodontal treatment wasperformed, and reevaluated after 3 and 6 months .The following clinical parameters were evaluated: Pocket depth (PD), Clinical Attachment Level(AL), Bleeding Index (BI), Gingival Index (GI), Plaque Index (PI).Furthermore, GCF samples were taken and examined using ELISA-Essaysquantitatively for PGE2, IL-1ß and IL-6. The plaque samples were takensubgingivally with paper points before the SPT, and after 3 and 6 months.The DNA was isolated from all samples using High Pure PCR TemplatePreparation Kit (Roche). The Quantitative real-time PCR was accomplishedusing QuantiTect Probe PCR Kit (Qiagen) in Gene Amp 5700 Sequence DetectionSystem. A DNA fragment of the gene served as standard for the 16S rRNA of D.orale and D. fairfieldensis. Results: A significant gain of PD, AL, GI andBI was observed in the test group after 6 months comparing with baselineexamination. The immunological analysis showed the parallel reduction of theconcentration of IL-1ß- and der IL-6. The qPCR showed in contrast thesuccessfull reduction of SRB with partial recolonisation after 3 months,which was obviously after 6 months completed. Conclusion: The quantitativePCR is an adequate methode for detection of SRB prevalence in patients withperiodontal disease. Keywords: Parodontitis, parodontale SRB, Desulfomicrobium orale, mikrobiologische Parodontitis-Diagnostik, quantitative PCR