Miscibility of segmented rigid-rod polyimide (PI), viz., biphenyl dianhydride perfluoromethylbenzidine (BPDA-PFMB), and flexible polyether imide (PEI) molecular composites was established by differential scanning calorimetry. The composite films of BPDA-PFMB/PEI were drawn at elevated temperatures above their glass transitions. Tensile moduli of the films were evaluated as a function of composition and draw ratio. Molecular orientations of polyimide were determined by birefringence and wide-angle X-ray diffraction. The crystal orientation behavior of the 80/20 BPDA-PFMB/PEI was analyzed in the framework of the affine deformation model.