(Ethene + methanol) possesses an interrupted critical curve with an ll miscibility gap. The llg three-phase line extends over a small temperature interval of ΔT = 23.3 K, between a lower critical end point (LCEP) and an upper critical end point (UCEP). Using two different methods of measurement (optical high-pressure cell and on-line gas chromatography), the phase equilibria at 284.15 and 298.15 K were measured, all three regions: gl1, l1l2, and gl2, being obtained for the 284.15 K isotherm. For measurements with the optical high-pressure cell, the densities of the fluid mixtures were also obtained.