New block terpolymers of the poly[oxytetramethylene-block-(multi-meth terephthalate)-block-laurolactam] (aGT-b-PO4-b-PA12) with potential applications as elastomers have been obtained by melt polycondensation of dimethyl terephthalate or isophthalate (DMT, DMI), glycols (aG), poly(oxytetramethylene)diol (PO4, M-w approximate to 1000 g mol(-1)) and alpha,omega-dicarboxylic-oligolaurolactam (PA12 approximate to 2250 g mol(-1)). The degree of polycondensation (DP) of poly(multi-methylene terephthalate) aGT amounts to DPGT = 4 The influence of the number of carbons (a) separating the terephthalate groups as well as meta or para positions of the ester groups in the benzene ring of other blocks, on the synthesis, properties and structure of these elastomers have been evaluated. The influence of changes in chemical composition of ester block (GT) on the structure and thermal and mechanical properties of the terpolymers have been determined by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), wide-angle X-ray diffraction (WAXS) and other standard physical methods. The properties of aGT-b-PO4-b-PA12 depend upon the mutual interaction of PA12 blocks with PO4 blocks, whereas aGT with PO4 and aGT with PA12, respectively. The characteristic properties of the aGT-b-PO4-b-PA12 terpolymers is the large content of the interphase (w(iph) > 40%). The fraction of the interphase is dependent on the compatibility of aGT with PA12 blocks. The terpolymers prepared with the use of 3G and 4G exhibit the highest content of interphase. However, the 4GI-b-PO4-b-PA12 terpolymer has the highest degree of soft phase separation.