"Perfect comb" graft copolymers are synthesized via acyclic diene metathesis (ADMET) polymerization using well-defined ruthenium catalyst systems to yield precisely spaced polyethers along an unsaturated polyolefin backbone. The graft is placed in a symmetrical alpha,omega -dime prior to ADMET polymerization to ensure exact graft placement at each functional site along the polymer backbone-no mistakes are made. The polyether grafts are essentially monodisperse as shown by MALDI analysis, while the polyolefin backbone exhibits a dispersity of 2.0. Such well-defined poly(ethylene-graft-ethylene oxide) copolymers will be interesting in several applications.