Abstract: A folding bag according including front and rear pliable rectangular faces, each face including a rigid base panel region. When the bag is in its first, closed position, the front and rear faces lie flat against each other. When the bag is in its second, open position, the base panels, which are hingeably attached to each other, open up to form part of the bottom of the bag, with the pliable portion of the faces remaining substantially parallel to each other, separated by the two base panels. The sides of the bag are provided by pliable right and left faces that are pleated and mounted to the front and rear faces and to the bottom the base panels are hinged in such a way that when the bag is in its first, closed position, the right and left faces are tucked between the front and rear faces such that the closed bag is a rectangle of substantially uniform thickness.