The effect of film formation conditions on structure, mechanical properties and barrier properties of amylose and amylopectin films was studied. The films were prepared by solution-gel-casting of amylose and amylopectin from potato, with or without the addition of glycerol as plasticizer. Transmission electron micrographs showed that the network structure characteristic for the amylose gel was also found in the film state. The amylose films without glycerol plasticization exhibited a relatively high degree of B-type crystallinity, as revealed by wide-angle X-ray diffraction, whereas the unplasticized amylopectin films were amorphous. Although the addition of glycerol did not affect the crystallinity of the amylose films, glycerol-plasticized amylopectin formed B-type crystallinity, and the degree of crystallinity was dependent on the air humidity during film formation. The degree of crystallinity affected the mechanical properties of the amylopectin films, whereas the mechanical properties of the amylose films were influenced by the network microstructure. Oxygen and water vapour permeabilities were dependent neither on the degree of crystallinity in the films nor on the network structure. © 1998 Elsevier Science Ltd. All rights reserved.