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 ≥ 0.5 kU/l and 138 children chosen at random among those with cord blood IgE levels < 0. 5 kU/l were seen at a follow-up at 5 years of age. Based upon history and physical examination a diagnosis of definite atopy or no atopy was established. Allergy (IgE mediated) was defined as atopic disease combined with increased total IgE levels at 5 years of age. The cumulative prevalence of atopic disease was not influenced by cord blood IgE levels or atopic predisposition. Cord blood IgE levels had a low sensitivity as a predictor of atopic disease. A statistically significant correlation between serum levels of IgE at birth and at 5 years was however found (p < 0.001), and a significantly greater number of children with elevated cord blood IgE levels developed allergic disease before 5 years of age (p < 0.01). A cut-off limit of 0. 3 kU/l was superior to the originally suggested limit of 0. 5 kU/l. A total IgE level > 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 ≥ 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. In the case of the most serious atopic disease, allergic bronchial asthma, the positive predictive value was 20%, the sensitivity 87% and the rate ratio 68.