A total of 159 children selected at random were followed up from the age of 8 to 12 years regarding the development and cumulated incidence of atopic disease as well as serum IgE concentrations. The cumulated incidence, including healed cases, rose to 25.8%. The highest prevalence was found for allergic rhinitis (12.2%). Serum IgE concentrations decreased significantly in both healthy and atopic subjects, and indicated a peak in total IgE concentration in early school age. The allergy predictive value of elevated IgE concentrations was confirmed. Low concentrations of allergen-specific IgE were found in 14.1% of children healthy before and during the observation period, indicating that transient production of IgE antibodies is a normal phenomenon. Finally, the stability of IgE was excellent during the first 2 years at -20 degrees C but later on concentrations tended to decrease, especially in the lower range.