The influence of the addition of rape seed oil, linseed oil and hydrogenated rape seed oil to the diet for milking ewes and growing lambs on the concentration of cis-9, trans-11 octadecadienoic acid, a conjugated linoleic acid, in milk and meat was investigated. In Experiment 1, 24 fattened lambs of 22 ± 2 kg body weight were divided into four groups and fed control (without added fat) and experimental diets with the respective additions to the basic diet of 6% rape seed oil, linseed oil or hydrogenated rape seed oil. In experiment 2 four lactating ewes of 50 ± 5 kg body weight were fed a basic diet for milking sheep consisting of 60% concentrate and 40% meadow hay (control group), which was supplied with 4, 8 or 10% of fat in dry matter for the experimental groups. Supplementing diets for fattened lambs with 6% rape seed oil, linseed oil or hydrogenated rape seed oil had no effect on the CLA content in meat. Rape seed oil and hydrogenated rapeseed oil had no effect on the CLA content in milk, whereas the addition of linseed oil significantly increased (P < 0.05) the CLA level in milk.