The studies segmented polyester polyurethaneurea (PUU) elastomers based on 4,4'-diphenylmethane diisocyanate (MDI), ethylene diamine (ED) and polybutylene adipate(PBA) (M.W.1,975 and M.W.1,228) were studied by means of IR spectrascopy. The major IR bands of PUU were first assigned and the views were proposed for the bands at 1,600, 1,317, 1,520 and 1,230 cm-1 assigned by other authors. The reliable theoretical basis for the assignments of IR bands and the studies of hydrogen bonding in these elastomers has been proposed by use of deuteration and varying temperature. The results indicated that substantial hydrogen bonding mainly occurred in the aggregate region of hard segments, a small amount of hydrogen bonding can be formed at the interface between the soft and hard segments. It can be concluded from this work that the studied PUU materials were phase segregation.