Clinical and microbiological parameters in partially dentate and edentulous patients treated with oral implants were compared in this study. Twenty-four subjects including 9 males and 15 females, aged 33 to 70 were treated with 98 Brånemark fixtures. Plaque index, gingival index, pocket depth, implant mobility and crevicular fluid flow rate were measured. Latex agglutination tests identified the presence of Actinobacillus Actinomycetem-comitans, Porphyromonas gingivalis and Prevotella intermedia. Partially dentate patients accumulated more plaque than edentulous patients (P = 0.05), whereas crevicular fluid flow rate was significantly higher (P < 0.001) in the partially dentate population. Porphyromonas gingivalis and Prevotella intermedia were more frequently detected (P < 0.01) in partially dentate patients. These results indicate that the presence of natural teeth alter clinical and microbiological parameters which could in turn affect the long term success rate of implants.