This paper was attempted to investigate effect of angiotensin inhibitor (loading dose 25, 50, $100{mu}g/kg$ and maintenance dose 12.5, 25, $50{mu}g/kg/hr$) on the pharmacokinetics of furosemide (5 mg/kg i.v) in rabbit. The plasma concentrations of furosemide increased by angiotensin inhibitor and the relative bioavailability of furosemide increased from 118.1% to 193.2% by the inhibitor. The protein binding of furosemide decreased by angiotensin inhibitor in bovine serum albumin ($2.17;{ imes};10^{-4}M$) by equilibrium dialysis method. Consequently, dosage regimen of furosemide might be adjusted carefully when furosemide is administered with angiotensin inhibitor.