The structural characterization of poly(n-methylen-di-O-methyl-L-tartaramide)s with n = 3, 5, 7 and 9 has been carried out using optical microscopy, thermal analysis, X-ray diffraction and electron microscopy. X-ray diffraction of powder and fiber samples were analyzed together with electron diffraction patterns of single crystals obtained from isothermal crystallization in solution. Experimental results based on crystallographic data were used to build a crystal model using the Cerius program. This model is based in chain packing with an arrangement of hydrogen-bonded sheets, being the resultant crystal structure similar to the exhibited in conventional polyamides. (C) 2004 Elsevier Ltd. All rights reserved.