Thermoplastic starch (TPS) obtained from agricultural waste was blended with polypropylene (PP) for natural weathering studies. The agricultural waste material was obtained from seeds and tubers with a starch content of approximately 50%. Commercial-grade TPS and native tapioca-based TPS were also prepared for comparison. The biobased TPS/PP extruded sheets were exposed to natural weathering for six months and their deterioration in weight, tensile properties, thermal properties, and relative molecular weight were monitored. SEM micrographs revealed the formation of surface cracking and the presence of microorganisms. FTIR spectrum indicated an increase in the carbonyl index over time as a result of the formation of degradation products. TPS/PP blends made from agricultural waste showed a better resistance to natural weathering compared to the other high starch formulation. The higher starch content in the blend system encouraged the rapid degradation process due to the combined effect of UV radiation with oxidation, moisture, temperature, and microbial attack. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013