Thermoplastic potato starch was prepard. by coextrusion with glycerol and used for manufg. biodegradable composites by compounding with poly(butylene terephthalate). The starch and the composites were studied for structure by IR spectroscopy. The mech. properties of the products were also detd. The composites consisted of 2 immiscible phases and showed an ability to biodegradn. under action of amyloglucosidase. The methods for modification of starch were briefly reviewed.