Measurement of apparent viscosity for rheological fluids is extremely important for a variety of industrial processes such as transportation of slurries in mineral processing, petrochemical and chemical processing, rheocasting of metal matrix composite, etc. In the present work, a sand᎐water slurry system of varying sand concentration was taken up as a model rheological fluid. The apparent viscosity was measured under dynamic flow conditions and varying shear strain rate using a simple technique of impeller viscometry. From the measurement of impeller speed, impeller and vessel configuration and power input data, a correlation was developed for the apparent viscosity of the non-Newtonian sand᎐water slurry system employing Reynolds number and power number. The values of apparent viscosity obtained from the above correlation compared reasonably well with the experimental observations by the same authors and also the literature data for a similar slurry system. The technique reported in this paper can be effectively used to measure apparent viscosities of slurries which do not exhibit any flocculating, coagulating or degenerating behaviour under shear within the laminar and transition regime of fluid flow.