There are many clinical evidences that hyperuricemia is a risk factor for the development of peripheral carotid and coronary vascular diseases. However, the mechanism of elevated uric acid concentration in biological systems is not yet clear. In the present work Fourier transform infrared (FT-IR) spectroscopy was used to evaluate the mechanism of calcification and plaque formation in carotid arteries in hyperuricaemic patients. Comparison between the spectra of carotid arteries from patients with elevated uric acid values and spectra obtained from patients with normal uric acid values showed structural changes of the characteristic spectral bands in the region 4000-500 cm-1. These changes were related with changes in the concentration of the serum uric acid and the clinical history of the patients. The intensity decrease of the infrared bands in the region 1650-1500 cm-1 was associated with the decrease of the apolipoprotein ratio, ApoI/ApoII, which corresponds to HDL (High Density Lipoproteins) and the regulation of the LDL (Low Density Lipoproteins), which are related to oxidation stress. The infrared band at 1467 cm-1 indicated the presence of urea components as a result of the metabolic pathway. The shape and the intensity of the bands between 1250-900 cm-1 depend on the glycation-end products of the diseases. SEM-EDX chemical analysis showed fibril formation and molybdenum release in hyperuricaemic patients