This presentation will introduce a novel synthetic gene-carrier,hyperbranched polylysine (HBPL),which is structurally related to dendritic polylysine but possesses a randomly branched structure and is obtained in a one-step reaction from lysine.After outlining the synthesis and structural characterization of these hyperbranched polypeptides,theit toxicity,cellular internalization and trafficking as well as gene delivery properties will be discussed and compared with those of linear and dendritic polylysine analogues as well as polyethylenimine (PEI).Transient gene expression experiments with CHO DG44 cells revealed that the hyperbranched analogues were superior as compared to the dendritic and linear polylysine.Altogether,the results of this study indicate that hyperbranched polylysine is an interesting,alternative synthetic gene carrier.These polylysine-based polycations can be produced at low costs and in large quantities,are partially biodegradable,which may help to prevent cumulative cytotoxicity,and possesses transfection properties that can approach those of PEI.