We intend to identify the relationship between Klotho protein and elderly hypertension. Serous Klotho protein and nitric oxide (NO) which gathered from 79 elderly hypertensive patients, 30 elderly non-hypertensive patients and 25 non-elderly hypertensive patients were detected by ELISA and nitro-reductase method, respectively; and the comparison came from the former group and the last two groups. The results were as follows: Klotho protein absorbance (0.303 ± 0.096) and NO concentrations (43.95 ± 21.85 μmol/L) in elderly hypertensive group were lower than the elderly non-hypertensive group (0.489 ± 0.216) and (62.63 ± 21.26 μmol/L). So it shows that there was significant difference between the two groups (P < 0.01). And the result suggested that, except of the contribution of Klotho protein to the calcification of vessel wall and reduction of vascular elasticity, elderly hypertension may partially attributes to the reduction of serous Klotho protein, which leads to the shrinkage of endothelial function companied with decrease of NO.