The comparison of drug profiles to find links between confiscated drugs has typically been a time-consuming manual task. The computerized method developed by the authors approximates the profiles with selected peak areas that are then compared. If two samples are from the same batch, the profiles are similar and all the selected peak areas will show the same ratio. The computer excludes pairs of digitized profiles that have different peak area ratios but reports those that may originate from the same batch. The original profiles may then be examined more closely. This operation does not require the examination of a large number of obviously different pairs, so tedious manual work is avoided. The computerized method was applied to a set of amphetamine impurity profiles. From each profile, areas of selected peaks were fed to the computer. By using quotients of corresponding peaks, the computer found pairs of closely related profiles. With a sufficient number of peaks, the method is tolerant to variations in intensity between profiles, random peak area variations, and a few strongly deviating peak areas. The program was written in Q-basic from Microsoft and may be run on any IBM-compatible personal computer. The method may also be used for analyzing data from other forensic objects when the descriptors chosen are affected by errors like those described in this paper. 2 tables, 2 figures, and 3 references