The development of topical corticosteroids has enabled many dermatoses to be more effectively treated than previously, but there is also no doubt that misuse of these preparations can lead to troublesome local effects and potentially serious systemic problems. The most effective assay for comparing different compounds has been their vasoconstrictive activity, and this on the whole correlates well with clinical effect. To be effective, corticosteroid must be absorbed and the importance of concentration, occlusion, the type of vehicle, added penetrants such as urea and the anatomical site, on the amount of absorption and therefore on clinical activity has been demonstrated. Ointments have been shown to be more effective than creams but because of the considerable choice of potencies now available most dermatologists tend to prescribe the different formulations according to the wishes of the patient. For the same reason, dilution of the commercially marketed preparations is now not generally recommended. The main therapeutic activity of topical corticosteroids is their nonspecific anti-inflammatory effect, thought to be primarily a result of their action on the chemical mediators of inflammation. They have also been shown to be antimitotic which may well be relevant not only to the treatment of scaling dermatoses but also to their dermal thinning effect resulting from inhibition of fibroblasts. Combinations of corticosteroids with antibacterial and antifungal agents have been shown to be very effective in flexural eruptions and secondarily infected dermatoses. As a general rule, the use of topical corticosteroids in outpatients, unless badly misused, is not associated with any significant risk of adrenal axis suppression, but care must be exercised as to the amount prescribed, especially if large areas of the body are to be treated with highly potent preparations. Certain groups such as young children and patients with liver failure, and certain anatomical sites such as the flexures and face appear much more prone to side effects, and in these cases mild or moderate compounds should be used in preference to the stronger preparations.