The present invention relates to a starch composition comprising starch, a polymer that is substantially compatible with starch and has a weight-average molecular weight of at least 500,000 such that the polymer forms effective entanglements or associations with neighboring starch molecules, and preferably at least one additive to improve melt flow and melt processability. The additive may be a hydroxyl plasticizer, a hydroxyl-free plasticizer, a diluent, or mixtures thereof. The composition is melt processable on conventional thermoplastic equipment. The composition is especially suitable for uniaxial and biaxial extensional processes to make fibers, films, foams and like products.