In a double-blind comparative study, by 29 dermatological departments, the activity of hydrocortisone 17-butyrate (HC 17-B, Locoid®), triamcinolone acetonide (TA) 0.1% and hydrocortisone 21-acetate (HA) 1%, were compared in patients suffering from acute eczematous dermatitis, atopic dermatitis and psoriasis. After a 7-day period of observation, the results were evaluated by means of a χ2 test, and an Armitage test. The following results were obtained: in acute eczematous dermatitis HC 17-B was found to be superior to the placebo and equal to TA; in atopic dermatitis HC 17-B was found to be superior to the placebo and HA, equal to TA; in psoriasis vulgaris HC 17-B was found to be superior to the placebo, HA and T