The nonlinearity of the Bagley plot of a thermotropic copolyesteramide is interpreted on the basis of the Eyring theory. The results obtained show that this nonlinearity can be interpreted as mainly due to an increase of viscosity with pressure. The dependence of viscosity on pressure is shown to vary upon the type of texture present in the capillary, either the worm-like one developed at low shear rates or the ordered one developed at high shear rates.