The use of nucleic acids as therapeutics offers many potential benefits for treating disease. However, for these delicate yet potent biomolecules to be practical in the clinic, carrier vehicles are needed not only to protect the nucleic acids during transport in the body, but also release the biopolymers at the disease site. Polycations can meet the complex needs of nucleic acid delivery as they can condense the polyanionic nucleic acids to form stable polyelectrolyte complexes and, through appropriate design, can release the biotherapeutic at a target site. In this feature article, we review recent advances in the field, and indicate the ways in which future materials of this type might lead to enhanced therapies and treatments for currently untreatable diseases.