The primary ecological niche for suspected periodontal pathogens seems to be the subgingival area, even though periodontal pathogens are also frequently recovered from saliva. The interrelationship of different periodontal conditions and the salivary levels of suspected periodontal pathogens is not known. In the present study, salivary levels of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Campylobacter rectus, and Peptostreptococcus micros were determined by bacterial culture and related to clinical periodontal status in 40 subjects with either advanced, moderate, or initial/no periodontitis. Culture-positive subjects harbored the 5 bacterial species in mean numbers ranging from 2 x 10(5) to 6 x 10(7) colony-forming units (CFU)/mL saliva. A. actinomycetemcomitans was found in none and P. gingivalis in one of the subjects with initial periodontitis, whereas both species were found in 33% and 44%, respectively, of the subjects with moderate periodontitis and in 60% and 40%, respectively, of the subjects with advanced periodontitis. The mean numbers of CFU/mL of P. intermedia, C. rectus and P. micros were significantly higher in subjects with advanced periodontitis than in subjects with initial/no periodontitis. Ten patients with advanced periodontitis were treated mechanically and with adjunctive systemic metronidazole, and were re-examined 1 and 6 months after treatment. Periodontal treatment eradicated or significantly reduced the levels of salivary periodontal pathogens for half a year, whereas in untreated subjects, the levels and the detection frequencies generally remained fairly stable. In conclusion, the results showed that the salivary levels of periodontal pathogens reflect the periodontal status of the patient.