Twenty-five tooth and implant sites in nine patients were investigated for the presence of putative periodontopathic organisms, using specific DNA probes for Actinobacillus actinomycetemcomitans, Porphromonas gingivalis, Prevotella intermedia, Eikenella corrodens, Fusobacterium nucleatum, Treponema denticola, and Campylobacter recta. Five of nine patients showed a likelihood of transmission from tooth to implant sites. These patients also showed a high number of putative periodontopathic organisms present in the tooth sites tested. A significant risk was found of transmitting putative periodontopathic organisms from periodontitis sites to implant sites in the same mouth. An appropriate clinical protocol needs to be developed to address this issue. Schlagwörter: cross-infection, dental implant, DNA probe, osseointegration, microbiology