To find out a convenient and reliable method of. detecting low renin status, we employed intravenous furosemide injection as a stimulatory maneuver. The results thus obtained were compared with those from the postural stimuli and basal plasma renin activity (PRA) in relation to sodium excretion. Intravenous furosemide test was performed in 66 control subjects and 44 patients with essential hypertension. The results were as follow; 1) Mean PRA in control subjects rose from $2.5{pm}1.95$ ng/ml/hr (basal) to $4.5{pm}2.51,;5.2{pm}2.49;and;4.2{pm}2.44$ ng/ml/hr at 1, 2 and 3hrs after IV injection. One-hour response is more convenient in clinical practice. 2) Postural stimuli by assuming an upright posture for 3 hrs gave rise to considerable increase in PRA ($4.0{pm}2.92;from;2.4{pm}1.85$), but we found it less convenient than stimulation with furosemide. 3) The increase in PRA was much less marked in patients with essential hypertension as a whole ($2.9{pm}2.75$). Hyporesponsiveness to furosemide stimuli was found in 34.1%. Of these hypo responders, a third had a normal basal PRA, indicating the need for this kind stimulatory procedure. 4) Younger age group showed greater renin responsiveness than older age group after furosemide stimuli. Likewise mean age of low renin patients ($52.9{pm}5.38$ years old) was significantly higher than that of high and normal renin patients ($44.1{pm}13.78$ years old).