Ice slurries show great potential for use in low energy refrigeration and cold storage systems but their transport properties and ice particle agglomeration are not well understood. Determination of the rheology of ice slurries has proved very difficult mainly due to the low viscosity carrier fluids currently used. In this paper we accurately characterize the rheology of a series of ice particle suspensions using a vane geometry at –18 °C. The ice slurries have the same high viscosity continuous phase, so the effect of volume fraction of ice particles can be examined, and no phase separation occurs. The flow curves across the phase volume range of 9%–29% were characterized by a large zero-shear viscosity (eta0>10 000 Pa s), and a region where the viscosity shear thins dramatically. The shear thinning occurs at a critical shear stress that is regarded here as an apparent yield stress (sigmay). Above the yield stress, the slurries flow according to a power law relationship. The zero-shear viscosity and apparent yield stress scale with the phase volume (phi) according eta0~phi5 and sigmay~phi3.5, respectively. The large values of these exponents are in line with those found for strongly flocculated particulate suspensions. This suggests that the rheology at low stress is highly dependent on the interactions between ice crystals, and the aggregation process that causes a network structure to form. ©2005 The Society of Rheology.