Abstract: A sterilization apparatus for sterilizing the interiors of paperboard containers, wherein such apparatus is operative prior to the container being mounted on a mandrel of a mandrel assembly on which the container bottom closures are formed, closed and sealed. This is accomplished by providing nebulizing means for communicating a suitable sterilant fog through and onto the inside surfaces of the carton blank from the time that it is removed from a magazine and while being opened into a four-sided tubular shape, thereby greatly increasing the total interior sterilizing time available prior to the container being filled downstream, as compared to conventional sterilization processes which are operative after the bottom panels of the carton have been closed and sealed. Heated air is supplied to each mandrel of the mandrel assembly and applied to the interior of the container while the container is mounted thereon.