Poly(lactic acid), PLA, composites containing 0, 1, 3, and 5 wt % zeolite type 4A were prepared using extrusion/injection compounding techniques. Morphological characterizations were carried out by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Physical properties were evaluated by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) and mechanical properties by standard tensile testing. The morphological studies showed a homogenous dispersion of zeolite particles within the PLA matrix. As the fracture stress propagated, zeolite particles remained em-bedded into the matrix, indicating the existence of good interfacial adhesion between zeolite particles and the PLA matrix. The improvement in the interfacial adhesion was also confirmed by applying Nicolais-Narkis and Pukanszky models. The percent crystallinity of the PLA and the temperature-dependant elastic and viscous modulus of the composite increased with the proportion of zeolites. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 2262-2270, 2010