A method of enhancing the isolation of ribonucleic acids from samples of biological or cellular material is disclosed which uses a solution of an Agent during binding of nucleic acids onto a solid phase binding material which, after elution, enhances the recovery of RNA. Washing the solid phase and eluting the nucleic acid produces RNA in enhanced yield and/or purity. The use of the new method allows RNA to be captured and released in a form suitable for downstream processing in under five minutes. Preferred Agents according to the invention comprise monomeric, oligomeric, dendrimeric and polymeric organic compounds having multiple positive charges.