The highly sensitive and specific methods of molecular biology emphasize the frequency of subclinical infections in the genital tract tissues by the human papillomaviruses (HPVs). The purpose of this work was to investigate occult viral infections by the HPV type 6, 11, 16, and 18 in the gingival tissues. The Southern blot method with 32P-radiolabeled DNA probes applied under stringent conditions to 20 interproximal gingival papilla specimens revealed homologous viral sequences in 1 of 6 cases of adult periodontitis (HPV 16), 1 of 2 cases of rapidly progressive periodontitis (RPP) (HPV 6/HPV 11), 2 of 2 cases of acute gingivitis in psychiatric institutionalized patients (HPV 6; HPV 6/HPV 11), and 2 of 10 cases of acute gingivitis in AIDS patients (HPV 6/HPV 11/HPV 16; HPV 6). No periodontal or extra-periodontal specimen hybridized with the HPV 18 probe. Simultaneous hybridization with two or three HPV types was common (3/6 cases). The present detection of HPV 6, 11, 16 DNAs or related-DNAs in periodontal tissues without obvious clinical signs of viral infection suggests that the gingival epithelium may act as a reservoir.