This study was conducted with a view to improving medication management service by reviewing renal excretory drug prescription practices in our hospital for patients with decreased kidney function without intervention of pharmacists. The subjects were the outpatients to whom the doctors had prescribed drugs containing digoxin, cibenzoline, bezafibrate, levofloxacin, valaciclovir or dabigatran. We retrospectively reviewed their serum creatinine levels, sex, age, height, weight and the amount of the drugs prescribed. It was found that there are cases in which medication had been prescribed without serum creatinine testing or prescribed in excess of the amount needed. Furthermore, there were cases in which the renal function had been judged in all probability by age and serum creatinine levels alone. Based on these findings, we concluded that pharmacists should intervene in pharmacotherapy using renal excretory drugs. For the realization of this, it would be necessary to build a system within the Department of Pharmacy to support the pharmacotherapy.