The correlation between segmental orientability and unperturbed chain dimensions has been studied. Calculations are carried out by a matrix generation technique based on a two-parameter rotational isomeric state model with interdependent bond rotation. Orientations of vectors along backbone bonds (u(parallel to)) and perpendicular to the chain contour (u(perpendicular to)) have been considered as a function of first (sigma) and second (u(parallel to)) order interaction parameters along the chain. A linear relationship of the form D-0 congruent to 1.78 x 10(-3)(r(2))(0)/nl(2) for u(parallel to) and D-0 congruent to -1.63 x 10(-3)(r(2))(0)/nl(2) for u(perpendicular to) is obtained between the orientability of a chain of n bonds of length l, which is expressed through the configurational factor D-0, and the unperturbed mean-square end-to-end separation, provided that sigma less than or equal to 1.8 or omega greater than or equal to 0.6.