Increasing attention has been focused on contact sensitization to topical corticosteroids in the past several years. In most cases, allergy to topical corticosteroids occurs in patients with long-lasting eczematous diseases. Cross-allergy between topical corticosteroid molecules is very common, and four groups of cross-reacting molecules have been recognized. In this report, we describe a girl with atopic dermatitis and sensitized to hydrocortisone-17-butyrate who became sensitized to 6 alpha-methylprednisolone aceponate. Cross-sensitization between the two molecules is suggested.