Adenoviral conjunctivitis causes high socioeconomic costs due to high contagiousness and therefore the need for extended quarantine. To date the only potentially active, topical antiviral agent is povidone-iodine (PVI). The aim of this study was to investigate the effect of diluted PVI on free adenovirus and adenoviral infected cells as well as to evaluate the cellular toxicity of PVI on non-infected cells.PVI was diluted to a final concentration of 0.0008 %. Virucidal activity was measured IN VITRO using adenovirus 8 and A549 human epithelial cell cultures. Cytotoxicity effects on healthy cells after short- and long-term exposure to diluted PVI were measured in A549 cell cultures.Exposure to PVI at a concentration of 1:10 (0.8 %) completely extinguishes infectivity of free adenovirus after an exposure time of 10 minutes. PVI is less effective against intracellular adenovirus resulting in a decreased infectivity and viral activity for approximately one day with a narrow spectrum between toxicity and virucidal activity. Healthy epithelial cells can be exposed to PVI for up to 6 hours without a cytotoxic effect.PVI is highly effective against free adenovirus but less effective against intracellular adenoviral particles in already infected cell. Short- and long-term exposure of PVI causes little cytotoxicity for healthy cells. Therefore, administration of diluted PVI at a concentration of 1:10 is a potential option to reduce contagiousness in cases of adenoviral infections.