Amphiphilic hyperbranched polyester (H20-AM) with methacrylate end groups was synthesized based on hyperbranched aliphatic polyester (Boltorn(TM) H20). Narrow-dispersed crosslinkable vesicles were obtained by dissolving H20-AM in water, and characterized by laser light scattering and TEM. The hollow structural vesicle is composed of around 350 H20-AM molecules, having a radius of around 40 nm and (M) over bar (w) of 1.9 x 10(6) g.mL(-1). The vesicles were fixed by crosslinking of methacrylate groups to form shape-persistent structures.