Summary Purpose: We assessed the poten- tial influence of the origin, the smoking status and the age on subgingival microbial profiles of subjects seeking periodontal care in Swit- zerland today. Material and Methods: Subgingival samples were obtained from 182 subjects originating from 44 countries (56 native Swiss, 64 other European, 43 African, 19 others), seeking periodontal treatment at the School of Dental Medicine at the University of Geneva. Four periodontal microorganisms were quantified by direct hybridization with specific RNA probes. Results: Tannerella forsythia and Treponema denticola were ubiquitous (95.6%, 93.9%), and Porphyromonas gingivalis was frequently detected (89%). Counts correlated with the size of the microbial sample (total load). Aggregatibacter actinomycetemcomitans was detected in only 70 (38.4%) subjects. Counts were highly variable and unrelated to total load. Subjects less than 46.8 years old (me- dian age) had a higher risk to be positive than older subjects. Detection frequencies and counts of all four organisms were unrelated to the origin or the smoking status. Conclusions: Based on a clinical diagnosis of untreated periodontitis, positive outcomes of tests for T. forsythia, T. denticola and P. gingi- valis could be predicted with high confidence irrespective of a patient's origin, smoking sta- tus or age. Detection of A. actinomycetem- comitans was less frequent and depended on the age of the subject.