Radioallergosorbent tests (RASTs) with five common foods were performed in 183 patients with atopic dermatitis. The results showed that about half of the patients had type I allergy to at least one of the five foodstuffs. The RAST results correlated roughly to the severity of dermatitis. In each group of patients with mild, moderate and severe atopic dermatitis, positive RAST reactions to common foods occurred predominantly in patients who had a personal or a family history of respiratory atopy. Positive RASTs were rare in patients with pure atopic dermatitis who had neither personal nor family history of respiratory atopy. It seems likely that type I food allergy occurs predominantly in those patients with atopic dermatitis who have a predisposition to respiratory atopy.