The pressure-volume-temperature (P-V-T) properties of monodisperse alternating poly (ethylene-propylene) (hydrogenated polyisoprene) melts of varying molecular weights are measured at 0.1 MPa < P < 200.1 MPa, and 290 K < T < 510 K in a dilatometer-type apparatus. The Flory-Orwoll-Vrij (FOV), Modified Cell Model (MCM), Sanchez-Lacombe (SL), and the Statistical Associating Fluid Theory (SAFT) equations of state are found to correlate the experimental data with excellent accuracy, except either at low pressures and high temperatures, or at high pressures and low temperatures. On average, MCM and SAFT fit the data slightly better than FOV and SL. The equation-of-state parameters are found to be independent of molecular weight, especially for SAFT, as required by the theory.