The results of screening for irregular blood-group antibodies in 35,882 blood-specimens using the gel-test method were analysed. The samples came from different clinics and hospital units. 1,179 samples from 728 different individuals (3.2%) contained one or several irregular antibodies. The gel low ionic strength antiglobulin test detected Kell, Duffy, and Ss antibodies with a normal frequency compared to bibliographic data, whereas Kidd antibodies seemed to be abnormally infrequent. The best detection of Rhesus antibodies was obtained with the gel enzyme test (papain). The prevalence of cold, naturally occurring, anti-Lewis and anti-P1 antibodies was low. The gel enzyme test with papain-treated red blood cells seems to be necessary for detecting Lewis antibodies (only 10 out of 95 were detected with the gel low ionic strength antiglobulin test). As a counterpart, the gel enzyme test also detected many antibodies with doubtful clinical significance: anti-E and anti-Cw reacting only with the gel enzyme test, autoantibodies with Rhesus specificity (82 examples), antibodies mimicking Jka (4 examples) and S (1 example) specificities in individuals with the corresponding antigen.