Abstract: Objective To assess the correlation of electrolytes measurements between arterial blood and venous blood in senile patients. Methods Measurements of potassium, natrium and chloridion concentrations in 57 senile patients (61-95 years old) who underwent arterial blood gas analysis and simultaneous venous blood analysis admitted into our hospital from January to December in 2012 were compared. The data were analyzed by correlation and regression analysis. Results The concentration of arterial blood potassium (4.03±0.67) mmol/L was significantly lower than venous blood potassium (4.22±0.69) mmol/L (P＜ 0.01), so was arterial blood natrium (136.63±5.97) mmol/L vs venous blood natrium (141.84±6.16) mmol/L (P＜ 0.01). While the concentration of arterial blood chloridion (108.71±7.87) mmol/L was significantly higher than venous blood chloridion (104.08±6.62) mmol/L (P＜ 0.01). Electrolytes concentrations in venous blood were positively correlated with the concentrations in arterial blood, coefficients of correlation were 0.987 (P＜ 0.01), 0.950 (P＜ 0.01) and 0.967 (P＜ 0.01) respectively, and they all had the linear regression relationship. Conclusion The electrolytes examination results between arterial blood and venous blood are different and they are positively correlated. When the examination results of venous blood cannot be obtained, the revised measurements of arterial blood can be a preferable reference.