The successful delivery of nucleic acids to particu lar target sites is the challenge that is being add ressed using a variety of viral and non-viral delivery sys tems, both of which have distinct advantages and disadvantages. Non-viral vectors offer the advantag e of safety and flexibility over viral vectors, alt hough they lack efficiency. Dendrimers are novel, three d imensional polymers that have the ability to intera ct with various forms of nucleic acids such as plasmid DNA, antisense oligonucleotides and RNA to form complexes that protect the nucleic acid from degrad ation. The interaction between the dendrimers and t he nucleic acids is purely electrostatic where the cat ionic dendrimer condenses the anionic nucleic acids . Because cell membranes are negatively charged, the net positive charge of the dendrimer nucleic acid complex determines the transfection efficiency, alt hough highly cationic systems are also cytotoxic. T he nature of the dendrimer nucleic acid complex depend s on various factors like stoichiometry, concentrat ion of dendrimer amines and nucleic acid phosphates, as well as bulk solvent properties like pH, salt concentration, buffer strength, and dynamics of mix ing. This article aims to review the role of dendri mers as novel gene delivery vectors both in-vitro and in -vivo. Dendrimer based transfection reagents have become routine tools for in-vitro transfection, but in-vivo delivery of therapeutic nucleic acids rema ins a challenge.