<p>Background: &beta;-Cyclodextrin functionalized hyper-branched polyglycerol (HBCD: &beta;-CD-g-PG), a biocompatible polymer, has recently been proposed for delivery of poorly water soluble compounds.<br /> Methods: The present study examines the interaction of HBCD with RNA, utilizing a constant concentration of RNA and different HBCD/RNA ratios of 1/16 to 1/1, at physiological condition in an aqueous solution. Circular Dichroism (CD), UV-visible, FTIR spectroscopic methods, zeta potential and Dynamic Light Scattering (DLS) were used to analyze the particle formation, particle charge, particle size, aggregation, RNA conformation, binding constant and mode, and the effect of polymer complexation on RNA stability.<br /> Results: The results indicate that the interaction of RNA with HBCD leads to the formation of a linear dendritic supramolecule biopolymer with an overall binding constant of KHBCD/RNA= 1.25 &times; 10³.&nbsp;<br /> Conclusion: The small sized synthesized polymer can be considered as an appropriate system for preventing RNA aggregation and protecting the gene by host-guest interaction.</p>