Vand’s modified equation has been extended to include the effect of three‐body collisions of spheres under shear. Brinkman’s equation has also been extended to derive an equation for the relative viscosity of concentrated suspensions of spheres by considering the dynamic formation of shear‐induced doublets and triplets of the suspended particles under shear. Vand’s estimation of the immobilized liquid during collisions has been critically examined and the equations derived have been modified on the assumption that only a fraction of Vand’s estimation is actually immobilized. Some deviations of experimental data from theory have been discussed and all the equations derived are compared with the data.