The influence of vitamin B6 on linoleic (LA), alpha-linolenic (ALA), arachidonic (AA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid content in serum and liver of rats fed with protein-energy deficient diets for 90 d, was studied. To estimate the effect of dietary supplementation with vitamin B6 on the composition and level of fatty acids in the serum and liver of rats, two experiments were performed. In these experiments control rats were fed ad libitum semisynthetic isocaloric diets of 1,466.5 kJ/100 g (350 kcal/100 g) throughout 90 d while the examined rats were offered 50% and 30% of the previously determined daily intake of the diet consumed in the control group. The experimental diet was supplemented with vitamin B6 to the level 4-times higher than in the control diet. A reduction to the half consumption of a standard diet supplemented with vitamin B6 caused a significant decrease of LA and ALA in blood serum at 30 and 60 d. At 90 d of the experiment the value of LA was lower and the content of AA was higher in comparison to the control group. After 30 d of consumption of vitamin B6 enriched diet in rats subjected to feed restriction to only 30% of the control intake, an increase of ALA and a decrease of AA, EPA and DHA were noticed in serum. At 60 d an increase of DHA was observed. Ninety days of feeding this diet caused a significant increase of AA level. Feeding animals for 90 d with a vitamin B6 enriched diet, with limited consumption to 50%, caused a significant increase of ALA content in liver. Further limitation of this diet consumption to 30%, caused a significant decrease of LA and ALA and an increase of EPA content.