THE AIM OF THE STUDY: To estimate the influence of anthocyanins from Aronia melanocarpa on blood pressure, concentration of endothelin-1 (ET-1), serum lipids, fasting glucose, uric acid and membrane cholesterol in erythrocytes of patients (pts) with metabolic syndrome (MS). MATERIAL AND METHODS: The study comprised 22 healthy volunteers and 25 pts with MS treated with anthocyanins (3 x 100 mg/d) for 2 months. Waist circumference (> or = 80 cm for women and > or =94 cm for men), triglicerydes (TG) level >150 mg/dl (1.7 mmol/l), cholesterol-HDL (HDL-C) level < 40 mg/dl (1.0 mmol/l) for men and <50 mg/dl (1.3 mmol/l) for women, systolic blood pressure (SBP) >130 mmHg and/or diastolic blood pressure (DBP) >85 mmHg were inclusion criteria for patients with MS. Before and after 2 months of treatment the following parameters were determined: SBP, DBP, serum lipids (total cholesterol--TC, cholesterol LDL--LDL-C, cholesterol HDL--HDL-C, TG--by enzymatic method), membrane cholesterol in erythrocytes (method of IIcy), ET-1 (immunoenzymatic method), fasting glucose level was (colorimetric method), uric acid (enzymatic--colorimetric method). RESULTS: After two months therapy of anthocyanins from Aronia melanocarpa in comparison with baseline it was observed a significant decrease of: SBP (144.20 +/- 9.97 vs. 131.83 +/- 12.24 mmHg, p < 0.001) and DBP (87.20 +/- 9.9 vs. 82.13 +/- 10.33 mmHg, p < 0.05), TC (242.80 +/- 34.48 vs. 227.96 +/- 33.07 mg/dl, p < 0.001), LDL-C (158.71 +/- 35.78 vs. 146.21 +/- 34.63 mg/dl, p < 0.01), TG (215.92 +/- 63.61 vs. 187.58 +/- 90 mg/dl, p < 0.05), ET-1 (2.44 +/- 0.51 vs. 1.74 +/- 0.42 pg/ml, p < 0.001) and membrane cholesterol (4.85 +/- 0.65 vs. 2.81 +/- 0.54 mmol/Lpc, p < 0.001), uric acid and fasting blood glucose levels did not change significantly after study cessation. CONCLUSIONS: The results of our study show that anthocyanins from Aronia melanocarpa may be of benefit to patients with MS as for as atherosclerosis prevention is concerned. It seems to result from anthocyanins influence on blood pressure, serum lipid and endothelin-1 level.