Background: metabolic syndrome (MetS) - combination of insulin resistance with abdominal obesity, high blood pressure and dyslipidaemia - is associated with early, virulent atherosclerosis. Main pathogenic link in this process is dyslipidaemia with the inflammation in intimamedia of arteries. Purpose: To investigate whether serum amyloid A (SAA) concentration has influence on fatty acids composition (FAC) of high-density lipoprotein (HDL). Material and methods: We studied concentration of SAA and FAC of HDL in 88 patients with MetS (mean age 39.7+-3.4; 45 – males, 43 – females) and 16 healthy adults (mean age 39.7+-3.4; 8 – males, 8 – females). The MetS was diagnosed according to ATP III. SAA was measured by IFA, FAC was measured by gas chromatography. Results: Concentration of SAA was significantly higher in MetS patients compared to the control results. In FAC of HDL were found following changes: increase of saturated fatty acids, particularly myristic acid (5.3 fold) (which is characteristic of atherogenous process of high intensity), 1.8 fold decrease of stearic acid, decrease of unsaturated fatty acids, particularly oleic acid (1.63 fold), decrease of polyunsaturated fatty acids: linoleic, linolenic, arachidonic, docosahexaenoic (DHA) - (2.5 fold),and eicosapentaenoic acid (7.9 fold). Sitrong correlation was found between concentration of SAA and quantity of fatty acids: myristic (r=0.83, p<0.0001), palmitoleic (r=0.49, p<0.0001), linolenic (r=-0.56, p<0.0001), arachidonic (r=-0.48, p<0.0001), DHA (r=-0.67, p<0.0001). Conclusion: In MetS patients there was significant rise of serum concentration of SAA, that had strong correlation with changes of HDL FAC and could be possible cause of decreasing of their antiatherogenic activity.