The present invention relates to fatty acid analogues of the general formula (I): R.sub.1-[x.sub.i-CH.sub.2].sub.n--COOR.sub.2 wherein R.sub.1 is; a C.sub.1 C.sub.24 alkene with one or more double bonds and/or with one or more triple bonds, and/or a C.sub.1 C.sub.24 alkyne, and/or a C.sub.1 C.sub.24 alkyl, or a C.sub.1 C.sub.24 alkyl substituted in one or several positions with one or more compounds selected from the group comprising fluoride, chloride, hydroxy, C.sub.1 C.sub.4 alkoxy, C.sub.2 C.sub.4 alkylthio, C.sub.1 C.sub.5 acyloxy or C.sub.1 C.sub.4 alkyl, and wherein R2 represents hydrogen or C.sub.1 C.sub.4 alkyl, and wherein n is an integer from 1 to 12, and wherein i is an odd number and indicates the position relative to COOR.sub.2, and wherein X.sub.i independent of each other are selected from the group comprising O, S, SO, SO.sub.2, Se and CH.sub.2, and with the proviso that at least one of the X.sub.i is not CH.sub.2, and with the proviso that if R1 is an alkyne or alkene, then the carbon-carbon triple bond or double bond is positioned between the (.omega.-1) carbon and the (.omega.-2) carbon, or between the (.omega.-2) carbon and the (.omega.-3) carbon, or between the (.omega.-3) carbon and the (.omega.-4) carbon, which can be used for the treatment and/or prevention of proliferative skin disorders. More specifically the invention relates to the inhibition of proliferation and/or differentiation of keratinocytes.