In this method for separating glycosylated from nonglycosylated hemoglobin in blood by electrophoresis on cellulose acetate membranes, we exploit the affinity of low-molecular-mass dextran sulfate for the nonglycosylated fraction, which increases the mobility of the latter relative to that of glycosylated hemoglobin. After the membrane strips are cleared and stained, the two fractions are quantified densitometrically. As evaluated by use with blood from diabetics, results compare well with those by chromatography on short columns and by electrophoresis in commercial agar gel films.