It was found that alkylating, amino-nitropyridine was able to crystallize epitaxially in a matrix of polyvinyl alcohol (PVA). Its longest spacing lay upon the periodical spacing between highly oriented PVA chains, i.e. its alkyl chains were across PVA chains. The degree of crystalline orientation of alkylating amino-nitropyridine in a drawn matrix of PVA was markedly higher than that of PVA at the low draw ratio below 6, which suggested that its epitaxial growth progressed with selecting the micro-fibrils composed of the highly oriented PVA. One of possible models of this epitaxy structure has been deduced with using its crystal structure proposed in a previous paper, which well matches its X-ray diffraction patterns.