Shear stress relaxation modulusGs(t,γ) was determined for a well‐characterized thermotropic liquid‐crystalline polymer, poly[(phenylsulfonyl)‐p‐phenylene 1,10‐decamethylene‐ bis(4‐oxybenzoate)] (PSHQ10) by conducting step strain experiments for a range of shear strains (γ). A fresh specimen was employed for each step strain experiment. We found that while time‐strain factorability [i.e.,Gs(t,γ)=G(t)h(γ), whereG(t) is the memory function andh(γ) is the damping function] was applicable to theisotropicregion, it wasnotto the nematic region of PSHQ10. We further found thatpreshearingof a specimen decreased the magnitude ofGs(t,γ) considerably, suggesting that variations in the morphological state (i.e., domain texture) took place during shearing. The failure of time‐strain factorability for the PSHQ10 in thenematicregion is believed to be attributable to variations in its morphology as affected by the level of applied shear strains.