Shear induced birefringence was measured for dilute and semidilute rigid PTFE rod suspension. Orientational order of the rods is deduced from the birefringence data and compared with theory by Doi and Edwards′. Although the theory was for dilute solution, the renormalized data agree qualitatively with the theory even far into the nonlinear regime. At high shear the order parameter approaches a saturated value, and at low shear it depends on the shear rate square. The major discrepancy between the theory and experiment comes from the expected slowing down of rod reorientation at higher concentrations. At high concentrations, the slowing down is more than what can be accounted for by the macroscopic viscosity along.