We report on the direct comparison of gel centrifugation technique and tube testing for antibody (AB) screening (ABS) under controlled routine conditions. 3,000 blood samples were screened for AB by gel centrifugation (ID-System, bromelin 37 degrees C and room temperature, indirect antiglobulin test with LISS) and a sensitive tube test (T; bromelin two-phase test 37 degrees C/room temperature and indirect antiglobulin test with 22% bovine albumin) in parallel. By ID significantly more relevant and potentially hemolytic AB (51 vs. 35 AB/1.7 vs. 1.2%) could be detected: anti-E 4, anti-C 1, anti-D 4, anti-CW 2, anti-C 2, anti-Jk (a) 2, anti-Jk (b) 1. 11 of these even remained negative in tube test when retested with increased sensitivity and taking additional (homozygous) test cells. In addition, naturally occurring but rarely hemolytic AB (35 vs. 23 AB/1.2 vs. 0.8%) were also more frequently detectable by ID: anti-Le (a) 6, anti-Le (b) 2, anti-P1 6. In contrast, only two AB were only positive in T: anti-Le (a) 1, anti-Le (ab) 1. The main disadvantage of ID was its frequent positivity (7.7 vs. 4.3%) due to irrelevant cold AB (anti-I, anti-HI, anti-H) and unspecific factors. This can be partly reduced by omission of the bromelin test at room temperature (ID 3.0%, T 1.5%) as the detection of relevant AB is not affected. The frequency of naturally occurring AB was still the same as in T (0.7%) when bromelin at room temperature was omitted in both techniques. Further advantages of ID are simplicity, small volumes of sera and reagents and easy evaluability.