An air jet carton reopening apparatus for use with an article cartoning machine. The apparatus produces a stream of pressurized gas or a gas mixture that opens carton sleeves to receive articles for packaging. The air jet apparatus comprises a gas emitting mechanism, a gas supply connected to the gas emitting mechanism, and a positioning mechanism constructed and arranged to dispose the gas emitting mechanism operationally adjacent to the carton sleeves. The stream of pressurized gas is directed at the carton sleeve such that it opens and maintains the relatively rectangular dimensions of the carton sleeves to permit the article cartoning machine to successfully load articles into an optimally sized carton.