This review focuses on the recent developments in study of cationic lipids as carriers for DNA delivery. Emphasis is placed on a class of compounds as exemplifies by their similarity in structures and transfection activities. The technical aspects are also reviewed on how to prepare DNA-lipid complexes and to perform transfection. A brief discussion of the current views on the mechanism of cationic lipid-mediated DNA transfer is intended to provide new prospects for future developments and further improvement of the current systems.