Hemoglobin A(2) (HbA(2)) comprises about 2.2% of the total hemoglobin in the erythrocytes. The separation and quantitation of this minor hemoglobin by capillary electrophoresis (CE) using an arginine Tris buffer is described. Some of the variables affecting the accuracy and precision of HbA(2) quantification are investigated. Furthermore, the quantification of this hemoglobin by CE is compared to that of a microcolumn chromatography method. The CE method is better suited than the microcolumn method for measuring HbA(2) in the sickle cell trait.