The inertia of the fluid and the inner cylinder in co-axial cylinders rheom
eter have a great influence on the unsteady flow of non-Newtonian fluid. In
the paper this phenomenon is studied minitely and a method to correct the
measured results for an unsteady flow in the rheometer is proposed. It was
found that the inertia effect of a fluid can be ignored when the gap betwee
n cylinders is smaller and the inertia effect of the inner cylinder can be
represented with a vibration equation. Using the equation changes of Huang'
s blood constitutive parameters are observed.