The effects of deep frying in sunflower oil or pork fat on the fatty acids (FAs) of silver carp (Hypophthalmichthys molitrix) and common carp (Cyprinus carpio) fillets were determined. The use of sunflower oil and pork fat for frying increased the proportion of polyunsaturated (PUFAs) and saturated fatty acids (SFA), respectively, in the fish fillets. In the fried fish fillets, the linoleic acid content (C18:2n-6) increased after frying in sunflower oil, while n-3 PUFAs, in particular C20:5n-3 (EPA) and C22:6n-3 (DHA), decreased compared with their contents in raw fillets. The apparent retention values of n-3 PUFAs were higher in silver carp (69-78%) than in common carp (21-43%) when the fillets were fried in sunflower oil. After frying the fish fillets in pork fat, contents of SFAs, especially palmitic (C16:0) and stearic (C18:0) acids, were increased compared with the raw fillets. From the public health point of view, it is important to highlight that the ratio of n-6/n-3 in fillets of silver carp and common carp increased after deep frying in sunflower oil (2.61; 28.50), as opposed to frying in pork fat (1.20 7.99). Deep frying the fish fillets in sunflower oil increased the total fat content of silver carp fillets by about 85% and common carp fillets by about 343%, while frying in pork fat increased the total fat content of silver carp fillets by about 78% and common carp fillets by about 191%. The choice of culinary oils/fats affects the total FA contents and the fat composition of prepared, fried fish fillets.