Background: Claudin-1 expression is poorly characterized in anal intraepithelial neoplasia (AIN) from HIVpositive individuals. Aim: To investigate claudin-1 in situ expression in HPV-positive AIN lesions from HIV-positive individuals compared with non-dysplastic anal tissues. Materials and Methods: By means of immunofluorescence microscopy, claudin-1 was analyzed in 46 anal tissues: 18 AIN1; 14 AIN2/3 and 14 non-dysplastic specimens. Results: A higher proportion of cells with overexpression of claudin-1 were found in HIV-positive AIN lesions compared with controls. Overexpression of claudin-1 was most evident in AIN 2/3 lesions. HPV16 was detected in 21.8% anal specimens and HPV18 in 3.1%. A great diversity of 18 low-risk HPV types were detected, 40% of AIN specimens had multiple HPV types. Conclusions: Our data show that there is an over-expression of claudin-1 in HIV-positive AIN lesions compared with non-dysplastic anal biopsies. A high prevalence of HPV16 and diversity of HPV types was detected. The overexpression of claudin-1 in HIV-positive AIN specimens may play a role on the development of anal cancer, however further studies should be performed to better understand the role of claudin-1 in AIN and anal cancer development in the HIV-positive individuals.