To study the possibility of separation of limonene from cineole (the two main components of eucalyptus oil), we measured the vapor-liquid equilibrium of the ternary system d-limonene, 1,8-cineole, and supercritical ethene at 288 K and 298 K and pressures to 7.0 MPa. The experimental results show that supercritical ethene is not selective enough to be used as solvent in an extraction process. To model the experimental results, the Peng-Robinson equation of state with non-quadratic mixing rules was used. The binary parameters between ethene and each terpene component were assumed to be those obtained previously for the corresponding binary system. No ternary interaction parameters were used. Predictions are in semiquantitative agreement only.