Screening of the ICSN chemical library led to the discovery of 3-(4-chlorophenyl)-4-cyano-5-thioalkylthiophene 2-carboxylic acids as potentfarnesyltransferaseinhibitors. Enzymatic kinetic studies showed that this original FTI series belongs to the CaaX competitive inhibitorclass. Preliminary SAR studies allowed us to improve the IC50 from 110 to 7.5 nM.