Compatibility of polyvinyl pyrollidone(PVP) and hydroxypropyl, methyl cellulose (HPMC) has been investigated by solution viscometric, ultrasonic,, differential scanning calorimetric (DSC) methods and fourier transform infrared spectroscopic (FTIR) techniques. Ultrasonic velocity and adiabatic compressibility versus blend,composition. are plotted, and found to-be linear. The results obtained reveal that HPMC and PYP form a miscible blends in the entire composition range. FTIR spectroscopy demonstrated that there is strong intermolecular hydrogen bonding between carbonyl group of PVP and free hydroxyl group of HPMC.