The miscibility of poly(3-hydroxyvalerate) (PHV)/poly(p-vinyl phenol) (PVPh) blends has been studied by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The blends are miscible as shown by the existence of a single glass transition temperature (T-g,) and a depression of the equilibrium melting temperature of PHV in each blend. The interaction parameter was found to be -1.2 based on the analysis of melting point depression data using the Nishi-Wang equation. Hydrogen-bonding interactions exist between the carbonyl groups of PHV and the hydroxyl groups of PVPh as evidenced by FTIR spectra. The crystallization of PHV is significantly hindered by the addition of PVPh. The addition of 50 wt % PVPh can totally prevent PHV from cold crystallization.