A tetrahedron-shaped packaging bag made of a flexible film material and comprising in the region of a tetrahedron corner of the bag, a pouring part which protrudes from the bag in an essentially tubular manner and which is closed on the free end thereof. The opening cross-section in the region of the transition between the bag and the pouring part is stabilized by a reinforcement in the film material of the bag, said reinforcement extending in a manner transversal to the pouring direction (y) opposite the tetrahedron corner.