The statistical theory of nematic systems of semiflexible polymers is extended to polymer chains of finite length in the bulk. Isotropic-nematic transition temperature, entropy change, orientational order, and conformational order at the transition are computed as a function of chain flexibility and chain length, using the new worm-like chain model with limiting curvature developed recently. The theory can cover a wide range of chain flexibility and its results converge to those of the theory of rod-like particles in the limit of completely rigid chains. Absolute stability of the nematic phase at all temperatures is predicted within suitable ranges of chain flexibility and chain length. © 1984 American Institute of Physics.