Abstract: Psoriasis in mammals is relieved by topically administering naphthalenes of the formula: ##STR1## wherein: R.sup.1 and R.sup.2 are lower alkoxy or lower alkylthio;R.sup.3 is hydrogen, lower alkyl, lower alkoxy, optionally substituted phenyl, optionally substituted phenyl lower alkyl, optionally substituted phenyl lower alkoxy, amino, lower alkylamino, lower dialkylamino, halo, cyano, or S(O).sub.n R wherein R is lower alkyl; optionally substituted phenyl; optionally substituted phenyl lower alkyl; or optionally substituted heterocyclic aryl of three to nine ring atoms containing one or two heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur, and the pharmaceutically acceptable acid addition salts thereof; and n is 0, 1 or 2; andW is alkyl of one to seven carbon atoms.