Although allergy represents an important source of patient morbidity and healthcare utilization, there is little reliable information on the overall disease burden posed by allergic conditions in the UK. Focusing on the following conditions: allergic rhinitis, anaphylaxis, asthma, conjunctivitis, eczema/dermatitis, food allergy and urticaria/angioedema, we sought to (i) describe the prevalence, incidence and outcomes of allergic disorders; (ii) describe the NHS healthcare burden posed by allergic disorders; (iii) estimate the costs of allergic disorders from a healthcare perspective. Secondary analyses of data from the Health Survey for England, Scottish Health Survey, International Study of Allergies and Asthma in Childhood, European Community Respiratory Health Survey, Morbidity Statistics from General Practice 1991/1992, Royal College of General Practitioners Weekly Returns Service, Prescribing Analysis and Cost data, Hospital Episodes Statistics and national mortality data. Thirty-nine percent of children and 30% of adults have been diagnosed with one or more atopic conditions. Six percent of general practice consultations and 0.8% of hospital admissions are for allergic diseases. Treatments for asthma and other allergic disorders currently account for 10% of primary care prescribing costs. Direct NHS costs for managing allergic problems are estimated at over one billion UK pounds per annum. Allergic disorders are common throughout the UK, affecting males and females of all ages and peoples from all social classes and ethnic groups. They currently represent a substantial burden of morbidity and health service cost.