We extend the liquid-state theory of polymer fluids to include anisotropy a
s a key feature. The formalism is quite general. In determining the structu
re of anisotropic polymer fluids, it yields thermodynamic information as we
ll. Our first application is to describe the nematic phases of flexible pol
ymers, and to demonstrate a novel lyotropic transition. (C) 1999 American I
nstitute of Physics. [S0021-9606(99)52414-8].