Methods are described for the identification and preparation of high-affinitynucleic acid ligands to TGF.beta., PDGF and hKGF. Included in the inventionare specific RNA and ssDNA ligands to TGF.beta.1 and PDGF identified by theSELEX method. Also included in the invention are specific RNA ligands to hKGFidentified by the SELEX method. Further included are RNA ligands that inhibitthe interaction of TGF.beta.1 and hKGF with their receptors and DNA ligandsthat inhibit the interaction of PDGF with its receptor.