High-pressure phase equilibrium data were measured for the system linear low density polyethylene (LLDPE) + isohexane. The LLDPE sample was a hydrogenated polybutadiene (hPBD) and was nearly monodisperse (M-w/M-o = 1.19). Phase transitions were observed visually using a Cailletet apparatus for mixtures with polymer mass fractions from 0 to 0.25 at temperatures from 380 to 500 K and pressures up to 12 MPa. Cloud points, bubble points and three-phase liquid-liquid bubble points were measured. The data were modeled using the modified Sanchez-Lacombe (MSL) equation of state. Results are compared with data and model calculations for the same LLDPE with n-hexane. (C) 2006 Elsevier B.V. All rights reserved.