Structure and viscoelastic properties of segmented polyurethanurea (SPU) blends were investigated. The glass transition temperature (T-g) of poly(tetramethylene glycohol) (PTMG) in a soft-segment block of the component SPU increased with decreasing molecular weight of PTMG. The blend samples showed two T(g)s of PTMG in the temperature dispersions of the loss modulus (E ") and loss tangent (tan delta). The value of E’ in the leathery region for the blend specimens was strongly affected by the morphology. The blends were considered to have a morphology where PTMG differing in molecular weight was localized.