This paper describes the self-assembly of rodcoil inclusion complexes, polyethyleniminepoly(ethylene glycol)a-cyclodextrin (PEIPEGa-CD). It is demonstrated that a-CDs should exclusively thread on the PEG block in PEIPEG copolymers and the resulting complexes have both rigid block (PEGa-CD) and coil block (protonated PEI). By varying the rigid block fraction, aggregates with hollow spheres or rod-like particles could be formed simply by self-assembly in aqueous solution.