A new method of the synthesis of aliphatic polyurethanes from diamines arid diols or alternatively from alpha,omega-aminoalcohols using ethylene carbonate as a substitute of phosgene is presented. It has been found that the transurethanisation reaction between alpha,omega-bis(2-hydroxyethoxycarbonylamino)alkanes and diols containing six or more carbon atoms in a molecule carried out in the presence of tin coordination catalysts, leads to [n,m]polyurethane, and ethylene glycol formed as a side-product. In the case of using aminoalcohols, the reaction with ethylene carbonate leads to [n]polyurethanes. The polymerisation products were analysed by means of H-1 and C-13 NMR spectroscopy, as well as MALDI-TOF mass spectrometry. The influence of the reaction conditions on the chemical structure of the reaction products and a plausible reaction mechanism are discussed.