During examinations of 479 patients referred for atopic dermatitis and 520 with urticaria it was found that in the first group coexistence of these diseases was frequently occurring, and in the second group it was rare. Food allergens caused slightly more frequently episodes of urticaria than exacerbations of atopic dermatitis. Coexistence of urticaria with atopic dermatitis was particularly frequent in patients: a) with a high IgE titre, b) with a history of allergy in the families of both parents, c) in patients with respiratory allergy associated with skin lesions.