The esterification of the hydroxyl group of starch with DuPont Surlyn was considered as pretreatment method of starch before blending with polyolefins, In treating starch with Surlyn, two different reaction conditions were taken to optimize reaction conditions. First, the esterification reaction was carried out in 110 degrees C xylene with oleic acid as a catalyst. Second, the reaction was carried out in a 90 degrees C. mixture of deionized water and xylene with eerie ammonium nitrate (CAN) as an initiator. Starch granules would be swollen above the gelatinization temperature in water. In both cases, starch was modified by Surlyn to have good compatibility with low-density polyethylene (LDPE). The mechanical and theological properties were examined for blends of the treated starch and LDPE. This system may be one of the biodegradable polymer blends that sufficiently retain properties as a packaging film.