Abstract: A hopper extension device for attachment to a conventional combine hopper includes upper and lower rectangular frames which have a flexible wall structure secured thereto. The frame members of the upper and lower frames extend through sleeves at the upper and lower ends of vertical panels defined by the flexible wall structure. The hopper extension device is shiftale between erect and collapsed positions by a plurality of toggle link assemblies, which extend between and are connected to the upper and lower frames. The toggle linkage assemblies are vertically disposed in a locked over-center condition in the erect position and are horizontally disposed in the collapsed position. The panels of the flexible walls extend between the toggle links of each toggle link assembly when the latter are in the collapsed position.