This paper presents the effects of liquid polarity on the rheology of suspensions with particle sizes ranging from 2 to 150 μm. We have found that liquid polarity has a substantial effect on the non‐Newtonian behavior of suspensions of graphite particles, but only a slight effect on that of polystyrene suspensions. This may be attributed to the greater interparticular van der Waals‐London dispersion force for graphite than for polystyrene. The suspensions of polystyrene spheres become Newtonian at very high shear rates when the interparticular van der Waals force is negligible as compared to the hydrodynamic force. This high shear Newtonian limit of relative viscosity is in excellent agreement with the value predicted by the rigid sphere model for colloidal suspensions.