The effects of thermal and deformation histories on the theological behavior of thermotropic liquid-crystalline polymers (TLCPs) were investigated using a cone-and-plate rheometer. For the study, two TLCPs were used : (1) the copolyester consisting of 73 mol % hydroxybenzoic acid (HBA) and 27 mol % 6-hydroxy-2-naphthoic acid (HNA) (Vectra A900) having the clearing temperature (T-c1) close to or above thermal degradation temperature (ca. 350 degrees C) and (2) an aromatic polyester, poly [(phenylsulfonyl)-p-phenylene 1,10-decamethylene-bis(4-oxybenzoate)] (PSHQ10) having a T-c1 of 175 degrees C, which was synthesized in our laboratory. In the use of PSHQ10, we were able to control the initial conditions of the specimens before being subjected to shear flow in the nematic region by first heating a solvent-cast specimen to the isotropic state and then cooling slowly to the nematic region. This was not possible, however, for Vectra A900. We found that the first normal stress difference (N-1) of PSHQ10 in the nematic state is positive at shear rates (gamma) of 0.008-1.08 s(-1) tested, and that values of N-1 for Vectra A900 are also positive at gamma = 0.01-1.0 s(-1) tested when using, as a reference state, the true zero value of normal stress that existed before the sample loading began.