Sheep milk fat was enriched in bioactive conjugated linoleic acid (CLA) isomers by alk. hydrolysis with KOH (70-75% for 3h) and treated with urea to remove satd. fatty acids. After crystn. from EtOH at low temp. (-60 degrees C), an increase in content of CLA 9c, 11tC18:2 isomer from 2.1% up to 15.8% in the product was achieved. During the process, the contents of oleic acid 9cC18:1 and 11tC18:1 isomers increased from 29,2% to 59.3% and from 1.5% to 13.2%, resp. Furthermore, the CLA 9c, 12cC18:2 isomer contained in poppy and grape seed oils was isomerized to 9c,11tC18:2 and 11 c, 13tC18:2 CLA isomers with KOH at 185 degrees C for 3 h. The products contained 77.6% (poppy seed oil) and 79.5% (grape seed oil) of the both CLA after removal of satd. fatty acid with urea.