The dynamic shear response of a bulk Zr55Cu25Ni5Al10Nb5 metallic glass has been investigated in the vicinity of calorimetric glass transition temperature, T-g. Similar to other glass formers, the Zr base bulk metallic glass exhibits typical features of the dynamic glass transition. The intermediate fragility index, m, indicates that the Zr base alloy belongs to the category of relatively strong glass formers in the general classification scheme. On the other hand, the time temperature equivalence principle is found to be applicable for constructing the master curve of dynamic shear modulus as well as shear viscosity over the temperature range studied. Theses master functions can be fitted with phenomenological models, such as generalized Maxwell model, or a Kohlrausch-Williams-Watts ( KWW) relation, and therefore reflect a broad distribution of local structural relaxation time for dynamic glass transition in the Zr base bulk metallic glass. (c) 2005 Springer Science + Business Media, Inc.