Abstract: The disclosure relates to a process and a cleaning machine for seed, grain and similar goods, in which the cleaning is realized by means of air circulated in an enclosed path by at least one fan, the air passing the grain adjacent the discharge opening of the machine for the air-cleaned grain. In the machine the resistance to the air circulating in the enclosed path is adjusted such that the static O-point will be located in the vicinity of the discharge opening for the air-cleaned grain. Furthermore, for the purposes of the above-disclosed process, the fan cooperates with a duct for the cleaning air moving to the fan, and with a duct for the air recycled to the cleaning station at the discharge opening, the ducts being of roughly the same length.