A number of cytokinin reference compounds have been successfully separated by High Pressure Liquid Chromatography using columns of pellicular strong cation exchange resin and of pellicular polyamide. On polyamide, all cytokinins were eluted within 10 min with an aqueous buffer but on the cation exchange resin some cytokinins (generally those with bulky N(6)-substituents and in addition lacking an N(9)-ribosyl substituent) had excessively long retention times with aqueous buffer eluent. However, addition of methanol to the buffer enabled these cytokinins to be separated and eluted within a reasonable time. As small an amount as 5 nanogram of cytokinin could readily be detected by the procedures described.