In 12 experiments on 6 mongrel dogs, furosemide was given both orally and i.v. in a dose of 20mg/kg. Following i.v. injection, the blood concentration curve followed an open one-compartment model. The elimination half-lives after both oral and i.v. routes were nearly similar, i.e. 1.42 +10.13 and 1.13 +0.06 hours respectively. The apparent volume of distribution corresponded well to the total body water (about 60%), i.e. 69.64 +5.61 and 52.06+4.82% b.wt. after oral and i.v. routes respectively. The body clearance of this drug after i.v. and oral administration showed close values, i.e. 5.27 +0.19 and 5.96 +0.14 mg/kg(-1) min(-1) respectively. The systemic bioavailablity of furosemide after oral administration amounted to 77.13 +5.24% with a maximum blood conc. (Cmax.) of 22.73 +2.03 microgram/ml, 30 min after administration.