Abstract: Objective To observe the clinical responses to two plasma concentrations of tacrolimus in treatment of idiopathic membranous nephropathy stageⅡ. Methods A total of 90 patients diagnosed with idiopathic membranous nephropathy stageⅡthrough renal puncture biopsyin our hospital were randomly divided into two groups, with high tacrolimus plasma concentration of 7.5~10 ng/mL (including 7.5 ng/mL) and low tacrolimus plasma concentration of 5~7.5 ng/mL. The differences of remission rate, plasma albumin level, urinary protein level and side effects between the two groups were observed. Results The two groups in the remission rate had no statistically significant difference(P>0.05). In terms of plasma albumin level, at two months of treatment the elevated level in the high plasma drug concentration group was more significant than that in the low plasma drug concentration group with statistically significant difference(P<0.05); whereas,in other observation months the observed plasma albumin levels in the two groups had no difference of statistical significance(P>0.05). In terms of urinary protein level, the two groups had no difference of statistical significance(P>0.05). In terms of adverse drug effect, the incidence of adverse drug effect in the high plasma drug concentration group was higher than that in the low plasma concentration group, without difference of statistical significance(P<0.05). Conclusions Low plasma concentration of tacrolimus can achieve the same clinical responses as its high plasma concentration in the treatment of idiopathic membranous nephropathy.