Production of conjugated oil from linoleic acid rich oils has been described as early as 1930. Forty years later, conjugated linoleic acids, CLA, started to be regarded as potential anti-cancer and anti obesity agents related to, respectively, the cis-9,trans-11 and the trans-10,cis-12 isomers. For economical reasons soybean oil is the preferred starting material for CLA production. Alkali isomerization of linoleic acid is, at present, the most common and less expensive procedure for producing these compounds. The resultant mixture is normally composed of at least four isomers, with equal amounts of the cis-9,trans-11 and the trans-10,cis-12 isomers. The need of pure compounds for nutritional studies and/or human or animal consumption makes obligatory purification steps. Apart from commercial scale molecular distillation, enzyme technology appears the most promising tool for effecting CLA isomers enrichment.