This study was conducted to determine whether a particle size measurement apparatus (commonly referred to as the degradation sizer) could be evaluated by repeated tests of threshed tobacco samples. Six samples of flue-cured tobacco and twelve samples of burley tobacco were tested on the degradation sizer five to ten times each in order to determine the effect of repeated tests on measured particle size distribution. Repetitive tests of flue-cured tobacco samples were then conducted to determine the effect of sizer drive frequency and volumetric loading density on degradation sizer test results. The particle size distribution of the samples, as measured by the degradation sizer, was found to decrease linearly (average R2=.97) with repeated tests. The fraction of the sample which passed over the 1 × 1 screen decreased at an average rate of 1.78 percent of total sample weight per repetition (%/rep) for burley tobacco, 1.00%/rep for flue-cured tobacco. The combined fraction of the sample which passed over the 1 x 1 screen and the 1/2 x 1/2 screen decreased at an average rate of 1.31%/rep for burley and 0.52%/rep for flue-cured tobacco. Increased sizer drive frequency was found to increase the measured particle size distribution in the region around the standard operating frequency of 530 rpm. The measured particle size distribution was also increased by increasing volumetric loading density. The predictable linear decline of particle size distribution found to result from repeated tests made possible the use of threshed tobacco samples for evaluation of the degradation sizer.