Gene therapy refers to the delivery of foreign gene material into the target cell with the purpose of therapeutic effect, in order to correct a particular disorder, or introduce a new function into the cell. The most used vectors in gene therapy are adenoviruses, but the presence of neutralizing antibodies against frequent serotypes like adenovirus type 5 (Ad5), can be a limiting factor in their application. Thus, using rare adenovirus serotypes like adenovirus type 26 (Ad26) or adenovirus type 35 (Ad35) may be the solution. Adenoviruses use endocytosis to enter the cell and it seems that clathrin mediated endocytosis is major path of their internalization. Besides that, caveolar endocytosis plays important role in internalization of some viruses. It's not known if caveolae have a part in Ad5, Ad26 and Ad35 transduction efficiency. The aim of this study is to investigate the role of caveolin-1 in Ad5, Ad26 and Ad35 endocytosis. Human lung adenocarcinoma cells (A549) have been transfected with plasmid containing short hairpin RNA for caveolin-1. Stabile transfectants with supressed levels of caveolin-1 have been selected and enroled in analysis of transduction efficiency analysis with Ad5, Ad26 and Ad35. Lower levels of caveolin-1 caused lower surface expression of adenoviral receptors CAR, C46 i αvβ5 and higher expression of αvβ3. In correlation with changes in expression levels of adenoviral receptors, caveolin-1 silencing led to lower internalization of Ad5 and Ad26, and reduced transduction efficiency of Ad5, but did not cause any significant change in transduction efficiency of Ad26 and Ad35. Results of this study indicate that caveolin-1 might play important role in Ad5 and Ad26 endocytosis in A549 cells.