We have developed a rapid chromatographic method for determination of glycosylated haemoglobins by high-performance liquid chromatography with a new cation-exchange column. The haemoglobins are eluted with a three-step gradient in 7 min, and total assay time including re-equilibration of the column is 15 min. The method permits separation and quantitation of HbAlc, even in the presence of elevated levels of HbF. HbA1a, A1b and A2 can also be determined. The results correlate well (r = 0.94) with those obtained by the macro-column method of Trivelli et al. [New Engl. J. Med., 284 (1971) 353] for determination of HbA1c. The method has been fully automated by the use of an automatic injector. The within-assay and between-assay coefficient of variation of the method is 2-3%.