Abstract: A novel transdermal system for the percutaneous delivery of a hormone, including a carrier and an adhesive matrix, is disclosed. The matrix includes (a) 20-50 parts by weight of a poly(styrene-isoprene-styrene) triblock copolymer, (b) 30-60 parts by weight of a tackifyier resin, (c) 4-25 parts by weight of propylene glycol laurate, (d) 2-10 parts by weight of a compound selected from N-alkyl-2-pyrrolidones, wherein the alkyl group is a C.sub.4-- C.sub.15 group, (e) 0.01-2 parts by weight of a stabilizing agent, (f) 0.1-12 parts by weight of at least one hormone selected from the group consisting of oestrogenic and progestogenic components, and (g) 1-12 parts by weight of a vinyl acetate/N-vinyl-2-pyrrolidone copolymer. A method for preparing said system and the therapeutical use thereof are also disclosed.