Abstract: Cation exchange, resin of the polystyrene sulphonic type, manufactured by Sine Laboratories (Shanghai), was used in the isolation of alkaloids in several galenical preparations. The alkaloids of nux vomica, belladonna and ergot were adsorbed from acid or neutral media by passing through a 0.7 × 5cm column of the resin (degree of cross linkage 2%), at a flow rate of about 0.4—0.5 ml per minute, or by shaking in a flask with the resin. Coloured impurities adsorbed on the resin were removed by washing with 50% alcohol, and then the alkaloids eluted with 0.5 N HCl 50% alcohol (for strychnine and brucine), 1N HCl (for hyoscyamine), or 0.5 N NH₄OH 50% alcohol (for ergot alkaloids) respectively. Alkaloidal contents of the eluate were then determined spectrophotometrically and colorimetrically. The method is rapid and simple, and gives results close to the pharmacopoeical methods.