Structures of a poly(3,3-bis(chloromethyl)oxacyclobutane) (PBCMO) film on graphite formed by polymerization-induced epitaxy were examined. Ring-opening polymerization of BCMO with a graphite substrate in the reaction mixture resulted in formation of a solid film on the substrate, Subsequent rinsing of the substrate left an insoluble, ultrathin film of PBCMO on the surface. Atomic force microscopy indicates that the graphite surface is uniformly covered by a maze of thin fibers, having a constant height of 2-3 nm, width of about 15 nm and varying lengths up to 120 nm. This feature is quite different from the globular morphology seen on a solvent-cast film or flat patched patterns on a melt-crystallized film. The molecular resolution images obtained by scanning tunneling microscopy exhibit linear alignments of enhanced current sites forming a series of parallel lines. A basic unit in the periodic feature of the images consists of five parallel lines having three different contrasts with periods 6.3 and 28 Angstrom and an oblique angle of 70 degrees. The known bulk structures based on a planar zigzag, all-trans conformation are not in accord with this feature. Based on the previous studies of poly(oxacyclobutane), a new molecular structure of the polymer on graphite is proposed.