Abstract: Progressively-collapsible disposable container, of the type in which at least part (2) of the container lateral surface consists of a bellows structure including a plurality of adjacent folds (A-G), each fold being formed by two opposite surfaces of different width, characterised in that the larger-width surface (A-D) is stiffer than the smaller-width one (D-E). Preferably, the greater stiffness of the larger surface of the folds is a shape stiffness, obtained shaping the surface with a stiffening step-rib (A-C), having rounded-off edges, projecting outwards of the container.