Screening of total IgE in 1189 cord blood samples was conducted by Phadebas IgE PRIST in a one-year birth cohort 1983-1984 in Viborg, Denmark. 113 children with cord blood IgE levels > or = 0.5 kU/l and 138 children chosen at random among those with cord blood IgE levels 63 kU/l (geometric mean + 1 SD) at the age of 5 years can be regarded as being an elevated level. A cord blood IgE level > or = 0.3 kU/l in combination with atopic predisposition was predictive of allergic disease, especially allergic bronchial asthma. With regard to allergic disease, the positive predictive value was 26%, the sensitivity 33% and the rate ratio for development of allergic disease 4.(ABSTRACT TRUNCATED AT 250 WORDS)