Microcolumn chromatography and a new test tube method for quantitation of hemoglobin A2were compared with column chromatography on DEAE-Sephadex, starch block and cellulose acetate elec-trophoresis to ascertain their relative accuracy, precision, reproducibility and speed. One hundred seventy-four blood specimens, including 90 samples from genetically provenβ-thalassemia hetero-zygotes were examined. The mean Hb A2values in normal andβ-thal-assemia heterozygotes were: 2.3Z and 4.7%, respectively, determined by microcolumn chromatography; 2.3% and 4.9%, respectively, determined by a new test tube method; 2.5% and 4.6%, respectively, determined by column chromatography on DEAE-Sephadex; 2.6% and 4.8%, respectively, determined by starch block electrophoresis; and 2.4% and 4.8%, respectively, determined by cellulose acetate electrophoresis. Although all five methods were found to be reliable and reproducible, the microcolumn chromatographlc method and the newly developed test tube method using DE-52 cellulose are the most rapid, reproducible, economical, and well suited for large scale surveys.By microcolumn chromatography, 7,953 school children and 2,710 other cases were screened for the quantity of Hb A2. In these samples, 578β-thalassemia heterozygotes were detected.