Monte Carlo simulations are performed to measure the uniaxial ordering of chain segments in a polymer network submitted to a uniaxial strain. The polymer network is modeled by an ensemble of chains with fixed extremities on a cubic lattice. Excluded volume between all segments in the system is imposed. The orientation is measured on free segments diffusing in the stretched networks. The orientation is shown to vary as the inverse chain length, as expected from a mean-field model including local orientation-dependent interactions. Bimodal networks are also studied. It is shown that in this case also the induced orientation has a mean-field behavior.