Polyvinyl alcohol) (PVA) is extensively used in paper coating, textile sizing, and fabrication of flexible water soluble packaging films. PVA has found application also in pharmaceutical, biomedical and biochemical fields, due to its attractive characteristics, such as biocompatibility, biodegradability and good water-solubility . However, low deformability limits applicability of PVA when compliance is necessary. PVA and poly (vinyl acetate) - (PVAc) composite films (prepared by casting of two-component water-based system blends: a solution of the rigid PVA and emulsion of the compliant plasticized PVAc), show wide range of strength-deformation characteristic, which can be controlled by component ratio . Effect of small amounts (1 - 10 wt %) of nanoparticles: monmorillonite clay (MMT) and microcrystalline cellulose (MCC) on structural, thermal and strengthdeformation characteristics of PVA, PVAc and PVA - PVAc compounds was studied in this work. Both fillers are characterized by high surface free energy which ensures sufficient dispersibility of particles in water systems and potential compatibility with PVA and PVAc macromolecules. Despite the dissimilar chemical nature, particle size and shape of fillers, the strength-deformation characteristics of filled films unexpectedly differ little. Films containing MCC show somewhat higher values of the modulus of elasticity and tensile strength, due to more pronounced reinforcing ability of fiber-like cellulose particles, as well as because of presence of hydroxyl groups, which may form strong hydrogen bonds with the hydroxyl groups of PVA. Studies of mixtures containing MMT by XRD evidence that MMT particles exfoliates in PVA - PVAc water systems.