There is a growing body of evidence which supports the hypothesis of faulty immune regulation and autoimmunity or inflammatory processes as viable mechanisms of the pathogenesis of Alzheimer's disease. The aim of this study was to evaluate the IL-6 level in serum of patients with AD and to analyze the correlation between IL-6 and this disease. Serum samples from 47 patients with clinically diagnosed Alzheimer's disease (27 women and 20 men, mean age 70.43 +/- 10.82 years, range 40-89 years) as compared to 47 controls (25 women and 22 men, mean age 70.17 +/- 10.64 years, range 40-89 years) were analyzed for IL-6 by ELISA (R&D Systems). The interleukin-6 levels were significantly higher in AD patients (234 pg/ml, range 85-567 pg/ml) as compared to control group (67 pg/ml, range 38-181 pg/ml); p < 0.001. It was evident from the study that increased production of IL-6 cytokine is found in AD patients, suggesting abnormal cellular immunity in these patients. Interleukin-6 plays a role in the pathogenesis of Alzheimer's disease. Our results suggest that high peripheral IL-6 secretion levels may be responsible for acute-phase proteins observed in the serum of AD patients. We find these results very promising for the consideration of future treatment of AD patients.