In the research study, there were analyzed the basic chemical composition and fatty acids profile in the fat of cow’s and goat’s milk produced in certified organic farms in southeastern Poland. A total of 54 samples of cow’s milk were evaluated including 28 samples collected at the beginning of March (winter feeding season), 26 samples at the end of July (summer feeding), and 60 samples of goat’s milk (30 samples in each feeding season collected on the same dates as those of cow’s milk). The contents of the basic components of cow’s milk were proved to be higher (p ≤ 0.01) than that of the goat’s milk, irrespective of the production season. The amount of saturated fatty acids in the cow’s and goat’s milk fat was at the same level (in total: 70.08 % and 71.75 %, respectively); however, the goat’s milk was characterized by a significantly (p ≤ 0.01) higher (4.04 pp.) content of short-chain and medium-chain fatty acids (SCFA+MCFA). The amount of polyunsaturated fatty acids (PUFA) was significantly (p ≤ 0.01) higher in the cow’s milk. In the milk of the two animal species, an increase was reported in the amount of those acids during the summer feeding period (22 % in the cow’s milk and 27 % in the goat’s milk). This fact was mainly owing to the increase in the amount of conjugated linoleic acid (CLA; 38 % in the cow’s milk and 52 % in the goat’s milk), which should most probably be linked with the pasture forage in the animals food diet. The production season significantly impacted the content of 26 fatty acids out of the 37 analysed.