The E7 tumor antigen of human papillomavirus type 16 (HPV16) is a validated target for immunodiagnosis and immunotherapy of HPV-associated cervical cancer. Anti-HPV16 E7 antibodies in scFv format were isolated from a human antibody phage display library and characterized. With the aim of interfering with the oncogenic activity of E7 protein, the most reactive of the selected antibody fragments was expressed by eukaryotic vectors in different compartments of the HPV16-positive cervical carcinoma SiHa cell line. The intracellular antibodies (intrabodies) were tested for their ability of inhibiting cell proliferation. A significant inhibition was obtained targeting the intrabodies to the nuclear and secretory compartments whereas no significant effect was observed in case of cytoplasmic localization. Inhibition was highly specific as no antiproliferative effect was obtained either with the E7-specific intrabodies in HPV-negative cells nor with irrelevant intrabodies in SiHa cells.