Abstract: 1,8-Dihydroxy-9-anthrone derivatives, substituted in the 10-position by an unsaturated radical, are described which have utility as ingredients in human and veterinary pharmaceutical and cosmetic preparations and which are compounds of the structural formula ##STR1## wherein R.sub.1 represents a hydrogen atom or a --CO.sub.2 R'.sub.2 radical,R.sub.2 and R'.sub.2 identical or different, represent a hydrogen atom, a linear or branched chain alkyl radical having 1 to 6 carbon atoms, a cycloalkyl radical having 4 to 6 carbon atoms or a benzyl radical,or R.sub.1 and R.sub.2 taken together form a radical --CO--, and n is 0 or 1,with the proviso that when n is 0 and R.sub.1 is --CO.sub.2 R'.sub.2,R.sub.2 and R'.sub.2 do not simultaneously represent the radical CH.sub.3, and the isomers of the compounds of formula (I) and mixtures thereof.

Abstract: A method for the treatment of psoriasis uses a composition which contains in an appopriate vehicle for topical application at least one active ingredient corresponding to the formula: ##STR1## wherein R is a radical of the group represented by ##STR2## wherein R.sub.1 and R'.sub.1 are identical or different and represent H, methyl or ethyl.