The polymer structure determination and refinement of flexible coil poly-2,5-benzoxazole ABPBO and poly-2,6-benzothiazole ABPBT were performed. Refinement of the unit cell structure of polyp-phenylene benzobisthiazole PBO and polyp-phenylene benzobisthiazole PBT in a nonprimitive monoclinic unit cell was carried out in a similar fashion. Initial structural models were derived from x-ray studies of model compounds. Experimental structure factors were incorporated into the Linked-Atom Least-Squares LALS refinement method. The Structure of the benzimidazo-isoquinoline ladder polymer BBL was also investigated. BBL shows potential as an organic conducting polymer. The feasibility of BBL and similar systems to act as conducting polymers requires accurate molecular structure and crystallographic data for an understanding of the mechanical, optical and electro-optic properties. Keywords Order polymers, Rigid rod polymers, Ladder polymer, Fiber structure, Polybenzothiazoles, Polybenzoxazoles.