Peptides have been discovered which are capable of binding to andinternalizing with the human transferrin receptor (hTfR). The sequencesHAIYPRH (Seq. ID No. 1) and THRPPMWSPVWP (Seq. ID No. 2) are capable ofbinding to and internalizing with the human transferrin receptor. When thesemolecules were fused with other molecules, the fusion product was internalizedin cells expressing hTfR. The sequences have use for targeting other peptidesand proteins into cells expressing hTfR.