The aim of study was to investigate an influence of nutritional deficiency and dietary addition of vit. B(2), B(6) and folic acid on PUFAs content in rats' serum and liver. Limitation of consumption full value diet to 50% of its previously determined daily consumption, enriched with m/a vitamins, significant decreased of linoleic (LA) and alpha-linolenic (ALA) acids as well as distinctly increased arachidonic (AA) and docosahexaenoic (DHA) acids content in serum in 30th day. In 60th day lower content of AA and DHA fatty acids was found. Nutrition with such diet, lasting 90 days caused decrease of LA content and increase of AA. Diet limitation to its 30% of daily consumption decreased of eicosapentaenoic acid (EPA) and DHA in the 30th day, while AA and DHA content was increased in the 60th day. Distinct decrease of AA content and increase of EPA content were found in the 90th day of experiment. Use of diets, with limited consumption to 50% caused increase of LA and ALA acids content while AA and DHA acids content were significantly decreased in the liver, in 90th day. Limited consumption supplemented diet to 30% caused in liver significant decrease of LA and increase of EPA acids content.