Five obese subjects were studied during prolonged starvation. Then renin aldosterone system and urinary aldosterone excretion were studied during prolonged starvation and refeeding in five obese subjects. An uniform increase in aldosterone urinary excretion was observed in all subjects studied. A progressive increase in renin plasma activity was found in all patients along the starvation period with a striking additional increase after refeeding. The possible factors involved are discussed.