The main reason of death among chronically dialysis patients are cardio - vascular system diseases. According to "The Report on the Condition of Renal Replacement Therapy in Poland in 2007", these diseases are the cause of 53% deaths in Poland. The patients with chronic kidney disease (PChN) are particularly at risk of cardio - vascular complications. These complications occur on average 30 times more often than in the whole population, and among young dialysis people, these complications occur 300 times more often. In the development of cardio - vascular complications polyunsaturated Omega-3 acids (especially eicosapentaenoic acid - EPA and docosahexaenoic acid - DHA) take a special position. The reaction of polyunsaturated Omega-3 acids on the cardiovascular system results from the enrichment of phospholipids of cell membranes within EPA and DHA. It should be noted that their impact is dependent on the type of acid and on the dose. Docosahexaenoic acid reacts with lipids and lipoproteins, blood pressure, heart rate, amount of glucose, and eicosapentaenoic acid is responsible for antiplatelet effect.