BACKGROUND The detection of clinically significant antibodies to red blood cell antigens is important for the selection of compatible blood for patients. The conventional test tube technique (CTT) is commonly used as the gold standard test, but manual testing and visual detection of hemagglutination may produce errors. A more recently developed method, the column agglutination technique (CAT), facilitates ease of testing. OBJECTIVE To investigate the specificity and sensitivity of the CAT compared to the CTT for the screening of clinically significant antibodies from the Rh blood group. METHODS Standard antibodies to the Rh blood group, anti-D, -C and -E, were used as examples of clinically significant antibodies in transfusion science. The antibodies were serially diluted by two-fold, then reacted with screening cells with different antigen expression. The hemagglutination reaction was investigated using both techniques, and the grades and scores of the reactions were used to analyze the sensitivity and specificity of the CTT and CAT. RESULTS The CAT had a better sensitivity than the CTT. The lowest antibody dilution of 1:8192 could be detected using CAT, while a dilution of only 1:2048 could be detected with CTT. However, the CTT and CAT were equal in specificity. The 2 techniques specifically detected all antibodies to the screening cells. CONCLUSIONS Both the CAT and CTT showed 100% specificity. However, the CAT exhibited more sensitivity than the CTT, and can be used in substitution of, or in parallel with, the CTT technique for red blood cell phenotyping, antibody screening, identification, and crossmatching.