Atopic dermatitis is a common inflammatory skin disease that especially affects children and adolescents. Many environmental factors have been recognized as relevant in aggravating skin lesions of the disease. However, it remains to be determined whether foods play a role in worsening of skin lesions in children with atopic dermatitis. In the present study, we investigated whether foods play a role in irregular aggravation of skin lesions in children with the disease. The study population consisted of 69 patients aged 3–15 years with atopic dermatitis. They were hospitalized and open challenge tests were performed with suspected foods. Photographs of representative skin lesion sites were taken at baseline and before and after the challenge. We determined challenge-positive foods by evaluating the comparable before/after challenge photographs. One to three (average, 1.9) challenge-positive foods were confirmed in 52 (75%) of the 69 patients examined. Predominant offending foods were chocolate, cheese and yogurt. Specific immunoglobulin E values to offending foods were mostly negative. We asked patients to exclude challenge-positive foods from their diets. They were then discharged and followed up for 3 months at our outpatient clinic. Exclusion of the offending foods for 3 months brought about a remarkable improvement in the disease. These results suggest that foods play an important role in irregular aggravation of skin lesions in children with atopic dermatitis.