a method and device for quality controlling packets of cigarettes , whereby , as a packet is fed , in use , through a quality control station , an optical detecting unit acquires data relative to given portions of the packet , which portions are coated with material optically detectable at wavelengths outside the visible range ; the data detected by the optical detecting unit is compared with reference data , and the outcome of the comparison is used to determine acceptance or rejection of the packet ; in this way , the condition of the packet can be determined regardless of the graphics on the packet .