The crystal structure and crystallization behavior of a series of poly(ester amide)s derived from L-tartaric acid, 1,6-hexanediamine, and 6-amino-1-hexanol were examined. The study included aregic polymers containing 5, 10, and 20% of ester groups in addition to the syndioregic polymer containing equal amounts of amide and ester groups. X-ray diffraction data revealed that all the aregic poly(ester amide)s adopt the same crystal structure as the parent polyamide made of L-tartaric acid, and 1,6-hexanediamine. In this structure, chains are slightly compressed and arranged as in the alpha-form of nylon 66. Solid-state nuclear magnetic resonance (NMR) revealed that ester groups are excluded from the crystal phase except for the case of the syndioregic polymer. Isothermal crystallization kinetics was analyzed according to the Avrami theory. Crystallization rates were found to decrease regularly with increasing contents in ester groups and with increasing crystallization temperature. Avrami exponent values close to 2 were found whereas spherulitic morphologies were observed by optical microscopy. (c) 2006 Wiley Periodicals, Inc.