The objective of the research study was to assess the contents of conjugated linoleic acid (cis9trans11 C18:2) and trans C18:1 and C18:2 acids in normalized milk and in yoghurts made thereof; the yoghurts analyzed were both fresh and stored at 8 ± 1 ºC for 21 days. The yoghurts were produced on a semiindustrial scale using a thermostatic method. Flex®Premium 2.0 frozen yoghurt cultures were applied to produce them. The research study showed that the storage time of yogurts significantly (p < 0.05) impacted the reduction in the contents of conjugated linoleic acid (CLA) and trans isomers of C18:1 and C18:2 in the yoghurts. On the first day of storage, the fresh yoghurts were characterized by the highest content of cis9trans11 C18:2 and trans isomers of C18:1 and C18:2. The average content of CLA in those yoghurts was 3.16 mg/g of fat. The content of trans C18:1 was 15.28 mg/g of fat and the content of trans C18:2 was 4.48 mg/g of fat. The lowest content of those isomers was found in the yoghurts on the 21^st day of storage. The average contents of acids were as follows: conjugated linoleic acid: 1.95 mg/g of fat; trans isomers of C18:1 acid: 9.96 mg/g of fat; and trans isomers of C18:2 acid: 2.79 mg/g of fat. The content of CLA and the totals of trans C18:1 and C18:2 isomers in fat of the yoghurts analyzed were highly correlated.