The presence and the immunophenotype of Langerhans cells (LC) have been investigated in formalin-fixed, paraffin-embedded biopsies obtained from 14 patients with dental titanium implants in which periimplantar tissues had been removed after different intervals from implant positioning. For the phenotypic characterization of LC and other immunocompetent cells in periimplantar tissues the following antigens have been investigated: CD3, CD20, CD35, CD68, MAC387, S-100 Protein and HLA-DR. The immunohistochemical APAAP method has been employed for antigen detection. The study has revealed that rare LC are detectable in the basal epithelium and in the lamina propria of periimplantar tissues removed after 2 months from implant positioning. In these specimens, LC only showed S-100 Protein reactivity; the mild inflammation which was present in the lamina propria was mainly sustained by B-lymphocytes. In samples from patients with dental implant positioned more than a year before, a higher number of LC was detected; the LC were scattered throughout the epithelium and were also in close contact with abundant T-lymphocytes and macrophages in the lamina propria. In patients with long-standing implants, LC appeared immunoreactive to S-100 Protein and HLA-DR. The results of this study show that LC are present in epithelial and mesenchymal periimplantar soft tissues and that their number seems to increase with the duration of implants. The variation in number and in the phenotype of LC may suggest that LC play a relevant role in the immune interactions between host and dental implants which might be important in the complex mechanisms of integration of implants within bone.