Abstract: Novel farnesyl transferase inhibitors of general formula (I) ##STR1## preparation thereof and pharmaceutical compositions containing same. In general formula (I), R.sub.1 is Y--S--A.sub.1 -- (where Y is a hydrogen atom, an amino acid residue, a fatty acid residue, or an alkyl or alkoxycarbonyl radical, and A.sub.1 is a C.sub.1-4 alkylene radical optionally .alpha.-substituted in the >C(X.sub.1) (Y.sub.1,) grouping by an amino, alkylamino, alkanoylamino or alkoxycarbonylamino radical wherein the alkyl or alkanoyl portion contains 1-6 carbon atoms; each of X.sub.1 and Y.sub.1 is a hydrogen atom or X.sub.1 and Y.sub.1, taken toether with the carbon atom to which they are attached, form a >C.dbd.O grouping; R'.sub.1 is hydrogen or a C.sub.1-6 alkyl radical; X is an oxygen or sulphur atom; R.sub.2 is a C.sub.1-6 alkyl, alkenyl or alkynyl radical optionally substituted by hydroxy, alkoxy, mercapto, alkylthio, alkylsulphinyl or alkylsulphonyl.