Optimization of cationic liposomal complexes for in vivo applications is complex involving many diverse components. These components include nucleic acid purification, plasmid design, formulation of the delivery vehicle, administration route and schedule, dosing, detection of gene expression, and others. This review will primarily focus on optimization of the delivery vehicle formulation. These formulation issues include morphology of the complexes, lipids used, flexibility versus rigidity, colloidal suspension, overall charge, serum stability, half-life in circulation, biodistribution, delivery to and dissemination throughout target tissues. Optimizing all components of the delivery system will allow broad use of liposomal complexes to treat or cure human diseases or disorders.