Using Monte Carlo simulations, we have investigated the possibility of an orientational melting transition within a “rope” of CNTs. hen twisting nanotubes bundle up during the synthesis, orientational dislocations or twistons arise from the competition between the anisotropic interbute interactions, which tend to align neighboring tubes, and the torsion rigidity that tends to keep individual tubes straight. We mapped the energetics of a rope containing twistons onto a alttice gas model and found that the onset of a free “diffusion” of twistons, conrresponding to orientational melting, occurs at T_OM ≥ 160 K.