Abstract: Filled food products are made by cooking and extruding a casing, in the form of a closed loop in cross-section, moving it past a knife so that it becomes slit open and then introducing one or more fillings into the casing through inlet ducts which pass through the opening formed by the knife, a system of forces being arranged to close up the opening or at least, to prevent it from opening or widening. Introduction of the filling material is preferably spaced downstream from the knife, so that the opening can allow steam or other vapor evolved from the casing to escape.