This contribution reports new experimental data on the phase behavior of the binary system dimethylether (DME) + tripaimitin (PPP). The experimental work covers a temperature region between 275 and 450 K and pressures up to 12 MPa were applied. Near the critical point of pure DME a three-phase region liquid-liquid-vapor (l(1),l(2)g) was established. Although only an upper critical endpoint of this three-phase equilibrium could be determined experimentally, it is most likely that the system DME + PPP belongs to type-V fluid phase behavior in the classification of Van Konynenburg and Scott. Besides the fluid phase behavior of the system, also phase equilibria in the presence of solid PPP were measured. From earlier work it became apparent that a Group Contribution Equation of State is capable to model the vapor-liquid and liquid-liquid equilibria in related systems. Therefore, this equation also was chosen to model the fluid phase behavior of the system DME + PPR. (C) 2002 Elsevier Science B.V. All rights reserved.