Carbohydrate-deficient transferrins (CDTs), naturally occurring glycosylated transferrin proteins, are reported to be increased in the serum of individuals who consume large quantities of alcohol (ethanol). We compared two methods for the separation and quantification of CDT, using the same alcohol-dependent patients and age-, gender-, and race-matched controls as sources of samples for both assays. There was good correlation (r = 0.89) between the microcolumn anion-exchange chromatography/RIA (MAEC/RIA) procedure and the isoelectric focusing, immunoblotting, and laser densitometry (IEF/IB/LD) procedure. Receiver operating characteristic analysis suggested that the IEF/IB/LD procedure would perform slightly better than MAEC/RIA for the overall population. However, both assays were much more sensitive for the detection of heavy alcohol consumption in men, compared with women. Alcohol consumption in the week prior to CDT measurement correlated only weakly with the concentrations measured with either assay.