Topical corticosteroids (CS) are frequently used to treat of allergic contact dermatitis, so that their own potential for sensitization is rarely detected. However, increasing numbers of hypersensitivity reactions to corticosteroids have been reported during the last 10 years, and allergic skin reactions to over 50 particular compounds have been observed. CS must now be regarded as a rather frequent contact allergen, the prevalence being twice as high in women as in men. Contact allergy to CS is clinically characterized by a chronic and persistent, corticosteroid-resistant dermatitis. In general, hypersensitivity to CS is a type I and/or type IV mediated allergic reaction. Cross-sensitivity between individual corticosteroid preparations has been described owing to their closely related chemical structures (e.g. hydrocortisone and tixocortol pivalate). Contact allergy to CS can be confirmed by patch-tests, intradermal injection tests or application tests; because of the delayed appearance of positive skin reactions a prolonged evaluation period of up to 120 h is recommended. For routine screening the use of the patient's own material and of tixocortol pivalate and budesonide as test marker substances seems appropriate. The development of further marker substances is a target for ongoing research.