Cationic liposomes, consisting of synthetic amphiphiles and a socalled helper lipid, rapidly form complexes with DNA, known as lipoplexes. When incubated with cells in culture, the DNA can be delivered into the cell and becomes expressed. Because of these properties, lipoplexes are considered a useful alternative for viral vectors for in vivo genetherapy. Yet, many hurdles have still to be taken. These are illustrated in the present overview, which briefly describes the critical steps involved in overall gene delivery in vitro, ranging from lipoplex formation to nuclear penetration and delivery of the desired gene.