Alternating copolymers of maleic anhydride with vinyl ethers, bearing a 4′-methoxy-4-biphenylyl mesogenic group via an oligo(ethylene oxide) spacer, were synthesized and structurally characterized. From X-ray diffraction observations, a smectic E phase was observed. Smectic layers are single layers of ribbon-like polymer chains, with all pendant groups arranged in a single row and pending on the same side of the backbone. Mesogenic groups are oriented up and down at random, and polymer chains are aligned along the [110] direction of the rectangular lattice describing the packing of the pendant groups.