Correspondence to:

Background: Exposure to environmental tobacco smoke (ETS) increases the risk of respiratory illness in children but data are inconclusive regarding the risk of IgE sensitisation. Objective: To elucidate whether exposure to smoking prenatally and/or postnatally is related to IgE sensitisation in children at 4 years of age. Methods: As part of a prospective birth cohort study (BAMSE), a total of 4089 families with children answered questionnaires when the child was 2 months, 1, 2 and 4 years old on environmental factors and symptoms of allergic disease. Blood collected at age 4 years from 2614 children was analysed for IgE antibodies to common inhalant and food allergens. Odds ratios (OR) and 95