The invention relates to a method for processing data carriers, comprising the steps of supplying a batch of data carriers for processing, defacing the supplied data carriers and further processing the defaced data carriers, wherein during each step the quantity of data carriers of the batch is compared with a given quantity and a warning signal is generated if the thus determined quantity and the given quantity do not correspond. The invention further relates to a system for performing this method provided with a station for supplying data carriers, a station placed in series therewith for defacing the supplied data carriers and stations for further processing of the defaced data carriers placed in series with the defacing station, wherein the supply station and the defacing station are provided with means for determining a quantity of data carriers passing through the station, which quantity-determining means are connected to a control system. With the method and system according to the invention unsold data carriers, for instance CDs for which copyright payments have been refunded, can be destroyed in verifiable manner without the danger of these still being brought into commercial circulation.