Researchers obtained novel random copolyesteramides (PAE) in a two stage transesterification and condensation polymerization process conducted in the melt. The PAEs were obtained by using an oligoether with amine end groups having three different molecular weights. Oligobutylene terephthalate served as an oligoester sequence. Differential scanning calorimetry revealed two glass transition temperatures attributable to two phases existing in PAEs. The constant glass transition temperature value in the low temperature range suggested that the polyester phase had a constant composition regardless of the polymer composition. Dynamic mechanical thermal analysis confirmed the heterophase structure of PAEs and the associated elastoplastic properties. Extensive relative elongation at break, high elasticity, and low hardness of PAEs containing 50-60 percent by weight of oligoether-diamine are characteristic for elastomers with a number average molecular weight of +2100. 24 refs.