The paper presents the qualitative composition of the fatty acids in the selected fish oil available on the Polish pharmaceutical market. Determination of the fatty acids composition was performed by gas chromatography (GC-FID). The results showed that all the tested fish oil composition contained essential fatty acids (EFA). All tested fish oils were characterized by high content of fatty acids from the group of n-3 and n-6. Differences in the composition of fatty acids in the tested fish oil were observed. The Norwegian fish oil was the richest in n-3 acids, i.e. eicosapentaenoic acid (34.43%) compared to the other samples tested: Icelandic fish oil (7.95%); Scandinavian fish oil (7.01%); Norwegian lemon fish oil (8.34%); kaps fish oil (7.95%); Norwegian fish oil forte (10.90%) and Scandinavian multi-tabs fish oil (6.11%). The highest share of acids from the group EFAs ie. linoleic acid n-6 (6.07%) and α-linolenic acid, n-3 (1.02%) was found in Scandinavian multi-tabs fish oil.