A Method for the treatment of skin fibrosis with a peptide that inhibits TGF-.beta., and suitable compositions for its administration. The method includes in particular, the use of peptide P144, a compound that is a known inhibitor of TGF-.beta., for the treatment of skin fibrosis by topical application. The method is shown effective in an animal model of bleomycin-induced skin sclerosis, to a reduction both of the skin fibrosis and of the content of soluble collagen, without any signs of systemic toxicity being detected. This shows that P144 is effective for topical application in mammals for treating fibrotic skin diseases and pathological scarring of the skin. For the administration of this peptide, stable compositions are also supplied, with pleasant appearance without being greasy, with good spreading characteristics and with a viscosity that permits it to be processed easily in industrial plant, and which are suitable for administering the peptide to humans.