Seed polypeptide patterns and esterase isozyme characterization in the seed proteins of the four populations of Aconitum atrox (Bruhl) Muk. syn. A. balfourii Stapf were studied. Different populations showed comparable polypetide patterns with some quantitative differences. A number of high (>76 kDa), intermediate (60-30kDa) and low (30 kDa) molecular mass polypeptides were resolved in the seed protein extracts of all the populations. Certain polypeptides were observed population specific and few were detected with low staining intensity. Esterase characterization revealed that some of the isoenzymes of the esterase were specific to a particular population and others were common in all populations. In conclusion, although A. atrox has acquired threatened status, the natural populations exhibit considerable polymorphism in seed polypeptides and esterase isoenzyme characterization.