Marked augmentation of urinary aldosterone excretion following furosemide administration was observed in previous experiment. In this study, author measured the changes of aldosterone secretion after furosemide administration in normotensive young volunteers with high sodium intake. After intravenous injection of $1.2-^3H-aldosterone$, urine samples were collected in course of time until 24 hours after the injection. Furosemide administration was done at 30 minutes prior to aldosterone injection. Specific activities of $^3H-aldosterone$ during and after diuresis were measured and aldosterone secretion rates were calculated dividing the doses by specific activities. Results were as followed 1. Furosemide resulted in a marked increase in urinary aldosterone excretion. 2. Furosemide lead to an increase in both sodium and potassium excretion. 3. Aldosterone secretion rate was also increased during furosemide diuresis, but the rate was smaller than that of urinary excretion. 4. Continuous modest increase in aldosterone secretion rate was shown after diuresis and total excess amount of aldosterone secretion for 24 hrs was equivalent to the amount of aldosterone excretion produced by diruesis. 5. Abrupt marked loss of circulating aldosterone produced by diuresis was supplemented by long lasting increase in secretion for over twenty four hours.