Objective:To discuss the influence of different vancomycin administration dosage in elderly patient's through blood concentrations and renal function.Methods:The clinical data about 113 elderly patients treated from January 2016 to December 2018 in our hospital was reviewed. After therapy, the through blood concentrations, administration dosage and renal function changes were detected to analyze their relationship.Results:The peak plasma concentration of 113 elderly patients was significantly higher than that of the young and middle-aged group ( P<0.05). Plasma concentrations in 185 cases were detected, including 35 cases with through blood concentrations<10 mg/L, 71 cases at 10-20 mg/L and 79 cases at >20 mg/L. There were 15 cases with 0.5 g/d of vancomycin, 96 cases at 1.0 g/d, 54 cases at 1.5 g/d and 20 cases at 2.0 g/d. The through blood concentrations among patients with different daily doses were significantly different ( P<0.05); at 1.0g/d, the ratio with through blood concentrations at 10-20 mg/L was the highest; serum creatinine (Cr) and blood urea nitrogen (BUN) contents in patients with through blood concentrations >20 mg/L were higher than those at <10 mg/L and 10-20 mg/L ( P<0.05); before treatment, Cr and BUN contents among groups were not significantly different ( P>0.05); among 113 elderly patients, the results indicated 21 renal function impairment cases and 92 normal renal function cases. The daily doses and through blood concentrations in renal function impairment group were higher than normal group ( P<0.05); BUN contents in renal function impairment group were higher than normal group while endogenous creatinine clearance rate was lower than normal group ( P<0.05); before and after treatment, BUN contents in groups were not significantly different ( P>0.05); after treatment, endogenous creatinine clearance rate for two groups was lower than before ( P<0.05); the results indicated that renal function was negatively correlated with vancomycin administration dosage and positively correlated with through blood concentrations ( P<0.05). Conclusions:During therapy, the renal function shall be closely monitored. According to patient's conditions and through blood concentrations, the vancomycin administration dosage shall be adjusted. In particular, the defined daily doses shall be reduced in renal function impairment patients, which through blood concentrations are kept at 10-20 mg/L.