Healthy human periodontal and peri-implant (ITI Bonefit) keratinized gingival tissues were studied immunohistochemically to evaluate the possible presence of structural differences in the extracellular matrix protein localization. Collagen types I, III, IV, and VII and fibronectin showed similar distribution in these tissues. Compared to the periodontal tissues, collagen type V was localized in higher amounts in the lamina propria of the peri-implant gingival tissues. Collagen type VI stained the periodontal tissues as a delicate microfibrillar network contrasting to the not well-stained peri-implant gingival tissues. The data show that structural differences between these tissues are present. The structural differences may be responsible for the defense of peri-implant keratinized gingival connective tissues to bacterial penetration, because of the high amount of the collagen type V component, which is responsible for the higher collagenase stability. Keywords: collagen, extracellular matrix, fibronectin, gingiva, peri-implant soft tissues