BACKGROUND: We analyzed the kinds and detection rates of irregular antibodies in 5,858 clinical specimens of the patients who visited Ewha Womans University Tongdaemoon Hospital between January, 1996 and December, 2000. We introduced the Gel test for the Type & Screening test in July, 1998 and tried to evaluate the change of the kinds and detection rates of irregular antibodies before and after introducing Gel test. METHODS: We detected the irregular antibodies using standard tube method in the first half period. In the second half period we detected the irregular antibodies by Gel-LISS method using 0.8% ID-Dia Cell I, II (DiaMed, Murten, Switzerland) and LISS/Coombs card (DiaMed, Murten, Switzerland). The irregular antibody was identified using DiaPanel (DiaMed, Switzerland) and LISS/Coombs card. When the irregular antibody was not identified, NaCl/Enzyme card (Diamed, Switzerland) was additionally used for confirmatory test. RESULTS: The detection rate of the irregular antibodies was 0.94%. In the first half period, 8 irregular antibodies were confirmed among total 98 cases with the detection rate of 8.16% and 7 of them were Rh antibodies. After introducing Type & Screening test, the irregular antibodies were identified in 47 cases among 5,760 total cases with the detection rate of 0.82%, but the low detection rate is thought to be due to pre-screening test. The identified antibodies included 19 cases(40.4%) of Rh antibodies and various other antibodies were detected. CONCLUSION: After introducing Gel test, various kinds of irregular antibodies were identified and this is thought to be due to improved sensitivity by the change of the method from the tube test to Gel test.