Drug analysis requires that the material be definitively identified as a controlled substance as prescribed in the legislation under which the scientist is working. On occasion, it is possible to identify the material on the basis of morphology alone. On other occasions, it is necessary to undertake phytochemical studies, and further still, DNA analysis. In this paper, the methods available for the identification of the plant materials of Cannabis, Catha edulis. Papaver somniferum and Erythroxylum spp. are reviewed.