Many disperse systems show a typical non-Newtonian flow at relatively high concentrations of the disperse particle. However, two Newtonian viscosities η ∞ and η 0 can be, respectively, determined at high and low rates of shear. Expect for very low particle content, η ∞/η s is proportional to exp( mϕ), where η s is a medium viscosity, m a constant which might reflect the particle-particle interaction and ϕ the volume fraction. In considering this relationship, a new type of equation which describes the relation between the zero shear relative viscosity η r0( ≡ η 0/η s) of the disperse system and ϕ is proposed as follows. ln η r0 = A( p)ϕ + am 3ϕ 2, where A( p), the Einstein-Simha constant, is a function of the axial ratio p of dispersing particles, and a is a constant (⋍ 0.03) which depends slightly on the particle shape. The equation has been compared with the experimental results obtained for several disperse systems. A number of disperse systems of spherical particles are described well by the choice A( p) = 2.5 and a = 0.027, and a system of rod-like particles with p = 50 by the choice A( p) = 215.6 and a = 0.033. m for rod-like particles is larger than that for spherical particles.