The viscoelastic properties of a set of star-shaped polystyrenes with 4-12 arms were studied in bulk by the tensile stress relaxation method. The zero-shear viscosity 0

the steady-state compliance Jc0 and other Theological parameters were determined from the relaxation modulus master curves. It was found that the zero-shear viscosity and the maximum relaxation time rm were strongly dependent on the size of polymeric molecules and could be described with the unperturbed specific viscosity or with the reduced molecular weight

no and τ1n increased with branch degree. It was directly proved that Joc of star polymers

whose arms are of same length

is independent of the number of arms. The Joc's of star polymers seem to be greater than those of linear polymers having the same molecular weight as span molecular weight of star.