Despite extensive research in the last decade on the use of cationic liposomes as gene transfer vectors and the development of elegant strategies to enhance their biological activity, these systems are still far from being viable alternatives to the use of viral vectors in gene therapy. Here, we highlight the most recent and relevant discoveries in thisfield, describe the main factors that influence the performance of cationic liposomes, and elucidate the barriers faced by these carrier systems as well as the mechanisms by which they mediate intracellular gene delivery.