A collapsible air freight container (10) comprises a standard base (12), a side panel (16) slideably hinged to the base and a back panel (18) which is hinged to the base which interlocks with the side panel. There is a side extension (20) which is generally trapezoidal to roughly conform to the shape of a side wall of a plane's cargo hold. A lid is slideably mounted on top of the container so that it can be slid relative to the back panel. The lid is arranged so that when fully retracted to the back of the container relative to the back panel, it may pivot to overlay the back panel. The container may be collapsed by retracting and pivoting the lid to overlie the back panel (18), folding the side extension (20), folding and sliding the side panel (16) into the base (12) and lowering the folded side extension (20) and then the back panel (18) and lid (40) into the base.