The authors describe the results of the early international efforts under the aegis of the United Nations from 1951 to 1967, as well as the sporadic investigations in this direction since 1968. The authors show that in spite of the application of modern computer-based technology, the primary obstacle to comprehensive opium characterization and typology is still the lack of an extensive reference collection of opium samples of known origin. A comprehensive literature search by the authors in 1993 revealed that there is no reliable, rapid method for opium origin determination. They began experimental work on the topic in 1993, making use of a computer technique that has already proved its usefulness in many other kinds of multifactorial correlations. Two analytical approaches that apply this computer-aided evaluation method were adopted, one that used HPLC quantitation of the five major opium alkaloids and another that is based on quantitation of nitrogen-containing volatiles by gas chromatography with a nitrogen phosphorous detector. Subsequently, principal component analysis (PCA) was applied to evaluate the data and to correlate alkaloid concentrations to the origins of the samples. PCA is a multivariate evaluation method that allows the optimal presentation of numerous features of a sample in a two-dimensional graph after computer-aided data reduction; it is thus superior to the discriminatory functions of the United Nations research program. PCA can be valuable for future origin determinations provided that the appropriate computer technique and the corresponding data from a sufficient number of authentic opium samples are available. 1 table, 4 figures, and 79 references